Editing World Wide Web (section)

== Function ==
{{main|HTTP|HTML}}
[[File:Internet Key Layers.png|thumb|The World Wide Web functions as an [[application layer]] [[communications protocol|protocol]] that is run "on top of" (figuratively) the Internet, helping to make it more functional. The advent of the [[Mosaic (web browser)|Mosaic]] web browser helped to make the web much more usable, to include the display of images and moving images ([[GIF]]s).]]

The terms ''Internet'' and ''World Wide Web'' are often used without much distinction. However, the two terms do not mean the same thing. The Internet is a global system of [[computer network]]s interconnected through telecommunications and [[optical networking]]. In contrast, the World Wide Web is a global collection of documents and other [[Web resource|resources]], linked by hyperlinks and [[Uniform Resource Identifier|URIs]]. Web resources are accessed using [[HTTP]] or [[HTTPS]], which are application-level Internet protocols that use the Internet transport protocols.<ref name="webinternet"/>

Viewing a [[web page]] on the World Wide Web normally begins either by typing the [[uniform resource locator|URL]] of the page into a web browser or by following a hyperlink to that page or resource. The web browser then initiates a series of background communication messages to fetch and display the requested page. In the 1990s, using a browser to view web pages—and to move from one web page to another through hyperlinks—came to be known as 'browsing,' 'web surfing' (after [[channel surfing]]), or 'navigating the Web'. Early studies of this new behaviour investigated user patterns in using web browsers. One study, for example, found five user patterns: exploratory surfing, window surfing, evolved surfing, bounded navigation and targeted navigation.<ref>{{cite journal|last1=Muylle|first1=Steve|first2=Rudy|last2=Moenaert|first3=Marc|last3=Despont|title=A grounded theory of World Wide Web search behaviour|journal=Journal of Marketing Communications|year=1999|volume=5|issue=3|page=143|doi=10.1080/135272699345644}}</ref>

The following example demonstrates the functioning of a web browser when accessing a page at the URL {{samp|<nowiki>http://example.org/home.html</nowiki>}}. The browser resolves the server name of the URL ({{samp|example.org}}) into an [[IP address|Internet Protocol address]] using the globally distributed [[Domain Name System]] (DNS). This lookup returns an IP address such as ''203.0.113.4'' or ''2001:db8:2e::7334''. The browser then requests the resource by sending an [[Hypertext Transfer Protocol|HTTP]] request across the Internet to the computer at that address. It requests service from a specific TCP port number that is well known for the HTTP service so that the receiving host can distinguish an HTTP request from other network protocols it may be servicing. HTTP normally uses [[List of TCP and UDP port numbers|port number 80]] and for HTTPS it normally uses [[List of TCP and UDP port numbers|port number 443]]. The content of the HTTP request can be as simple as two lines of text:
<syntaxhighlight lang="http">
GET /home.html HTTP/1.1
Host: example.org
</syntaxhighlight>

The computer receiving the HTTP request delivers it to web server software listening for requests on port 80. If the web server can fulfil the request it sends an HTTP response back to the browser indicating success:
<syntaxhighlight lang="http">
HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
</syntaxhighlight>

followed by the content of the requested page. Hypertext Markup Language ([[HTML]]) for a basic web page might look like this:
<syntaxhighlight lang="html">
<html>
  <head>
    <title>Example.org – The World Wide Web</title>
  </head>
  <body>
    <p>The World Wide Web, abbreviated as WWW and commonly known ...</p>
  </body>
</html>
</syntaxhighlight>

The web browser [[parsing|parses]] the HTML and interprets the markup (<syntaxhighlight lang="html" inline><title></syntaxhighlight>, <syntaxhighlight lang="HTML" inline><p></syntaxhighlight> for paragraph, and such) that surrounds the words to format the text on the screen. Many web pages use HTML to reference the URLs of other resources such as images, other embedded media, [[Client-side scripting|scripts]] that affect page behaviour, and [[Cascading Style Sheets]] that affect page layout. The browser makes additional HTTP requests to the web server for these other [[Internet media type]]s. As it receives their content from the web server, the browser progressively [[Browser engine|renders]] the page onto the screen as specified by its HTML and these additional resources.

=== HTML ===
{{main|HTML}}
Hypertext Markup Language (HTML) is the standard [[markup language]] for creating [[web page]]s and [[web application]]s. With [[Cascading Style Sheets]] (CSS) and [[JavaScript]], it forms a triad of [[cornerstone]] technologies for the World Wide Web.<ref>{{cite book|last1=Flanagan|first1=David|title=JavaScript – The definitive guide|page=1|edition=6|quote=JavaScript is part of the triad of technologies that all Web developers must learn: HTML to specify the content of web pages, CSS to specify the presentation of web pages, and JavaScript to specify the behaviour of web pages.}}</ref>

[[Web browser]]s receive HTML documents from a [[web server]] or from local storage and [[browser engine|render]] the documents into multimedia web pages. HTML describes the structure of a web page [[Semantic Web|semantically]] and originally included cues for the appearance of the document.

[[HTML element]]s are the building blocks of HTML pages. With HTML constructs, [[HTML element#Images and objects|images]] and other objects such as [[Fieldset|interactive forms]] may be embedded into the rendered page. HTML provides a means to create [[structured document]]s by denoting structural [[semantics]] for text such as headings, paragraphs, lists, [[Hyperlink|links]], quotes and other items. HTML elements are delineated by ''tags'', written using [[Bracket#Angle brackets|angle brackets]]. Tags such as {{code|lang=html|code=<img />}} and {{code|lang=html|<input />}} directly introduce content into the page. Other tags such as {{code|lang=html|code=<p>}} surround and provide information about document text and may include other tags as sub-elements. Browsers do not display the HTML tags, but use them to interpret the content of the page.

HTML can embed programs written in a [[scripting language]] such as [[JavaScript]], which affects the behaviour and content of web pages. Inclusion of CSS defines the look and layout of content. The [[World Wide Web Consortium]] (W3C), maintainer of both the HTML and the CSS standards, has encouraged the use of CSS over explicit presentational HTML {{as of|1997|lc=y|since=y|post=.}}<ref name="deprecated">{{cite web|url=https://www.w3.org/TR/REC-html40-971218/conform.html#deprecated|title=HTML 4.0 Specification – W3C Recommendation – Conformance: requirements and recommendations|publisher=World Wide Web Consortium|date=18 December 1997|access-date=6 July 2015|archive-date=5 July 2015|archive-url=https://web.archive.org/web/20150705040855/http://www.w3.org/TR/REC-html40-971218/conform.html#deprecated|url-status=live}}</ref>

=== Linking ===
Most web pages contain hyperlinks to other related pages and perhaps to downloadable files, source documents, definitions and other web resources. In the underlying HTML, a hyperlink looks like this:
<syntaxhighlight lang="html" inline=""><a href="http://example.org/home.html">Example.org Homepage</a>.</syntaxhighlight>
[[File:WorldWideWebAroundWikipedia.png|thumb|Graphic representation of a minute fraction of the WWW, demonstrating [[hyperlink]]s]]
Such a collection of useful, related resources, interconnected via hypertext links is dubbed a ''web'' of information. Publication on the Internet created what Tim Berners-Lee first called the ''WorldWideWeb'' (in its original [[CamelCase]], which was subsequently discarded) in November 1990.<ref name="W90">{{cite web |url=http://w3.org/Proposal.html |title=WorldWideWeb: Proposal for a HyperText Project |first1=Tim |last1=Berners-Lee |author-link1=Tim Berners-Lee |first2=Robert |last2=Cailliau |author-link2=Robert Cailliau |date=12 November 1990 |access-date=12 May 2015 |url-status=live|archive-url=https://web.archive.org/web/20150502080527/http://www.w3.org/Proposal.html |archive-date=2 May 2015}}</ref>

The hyperlink structure of the web is described by the [[webgraph]]: the nodes of the web graph correspond to the web pages (or URLs) the directed edges between them to the hyperlinks. Over time, many web resources pointed to by hyperlinks disappear, relocate, or are replaced with different content. This makes hyperlinks obsolete, a phenomenon referred to in some circles as link rot, and the hyperlinks affected by it are often called [[link rot|"dead" links]].<!-- Note: if "dead" isn't in quotes, this page will throw a false positive on template maintenance script runs. --> The ephemeral nature of the Web has prompted many efforts to archive websites. The [[Internet Archive]], active since 1996, is the best known of such efforts.

=== WWW prefix ===
<!-- WWW prefix redirects here -->
Many hostnames used for the World Wide Web begin with ''www'' because of the long-standing practice of naming [[Internet]] hosts according to the services they provide. The [[hostname]] of a [[web server]] is often ''www'', in the same way that it may be ''ftp'' for an [[FTP server]], and ''news'' or ''nntp'' for a [[Usenet]] [[news server]]. These hostnames appear as Domain Name System (DNS) or [[subdomain]] names, as in ''www.example.com''. The use of ''www'' is not required by any technical or policy standard and many websites do not use it; the first web server was ''nxoc01.cern.ch''.<ref>{{cite web |url=http://w3.org/People/Berners-Lee/FAQ.html |title=Frequently asked questions by the Press |first=Tim |last=Berners-Lee |publisher=W3C |access-date=27 July 2009 |url-status=live |archive-url=https://web.archive.org/web/20090802051415/http://www.w3.org/People/Berners-Lee/FAQ.html |archive-date=2 August 2009}}</ref> According to Paolo Palazzi, who worked at CERN along with Tim Berners-Lee, the popular use of ''www'' as subdomain was accidental; the World Wide Web project page was intended to be published at www.cern.ch while info.cern.ch was intended to be the CERN home page; however the DNS records were never switched, and the practice of prepending ''www'' to an institution's website domain name was subsequently copied.<ref>{{cite web |last=Palazzi |first=P |date=2011 |url=http://soft-shake.ch/2011/en/conference/sessions.html?key=earlydays |title=The Early Days of the WWW at CERN |archive-url= https://web.archive.org/web/20120723105704/http://soft-shake.ch/2011/en/conference/sessions.html?key=earlydays |archive-date=23 July 2012 |url-status=dead}}</ref>{{better source needed|date=August 2022}} Many established websites still use the prefix, or they employ other subdomain names such as ''www2'', ''secure'' or ''en'' for special purposes. Many such web servers are set up so that both the main domain name (e.g., example.com) and the ''www'' subdomain (e.g., www.example.com) refer to the same site; others require one form or the other, or they may map to different web sites. The use of a subdomain name is useful for [[load balancing (computing)|load balancing]] incoming web traffic by creating a [[CNAME record]] that points to a cluster of web servers. Since, currently{{As of?|date=September 2023}}, only a subdomain can be used in a CNAME, the same result cannot be achieved by using the bare domain root.<ref>{{cite web |url=https://medium.freecodecamp.org/why-cant-a-domain-s-root-be-a-cname-8cbab38e5f5c |title=Why a domain's root can't be a CNAME – and other tidbits about the DNS |first=Dominic |last=Fraser |date=13 May 2018 |work=FreeCodeCamp |access-date=12 March 2019 |archive-date=21 April 2024 |archive-url=https://web.archive.org/web/20240421053219/https://www.freecodecamp.org/news/why-cant-a-domain-s-root-be-a-cname-8cbab38e5f5c |url-status=live }}</ref>{{Dubious |reason=While CNAMEs are more flexible than the bare domain requiring an A Record, load balancing is certainly possible even for sites that skip www and use the bare domain — see, for example, Twitter.|date=July 2019}}

When a user submits an incomplete domain name to a web browser in its address bar input field, some web browsers automatically try adding the prefix "www" to the beginning of it and possibly ".com", ".org" and ".net" at the end, depending on what might be missing. For example, entering "{{not a typo|microsoft}}" may be transformed to ''<nowiki>http://www.microsoft.com/</nowiki>'' and "openoffice" to ''<nowiki>http://www.openoffice.org</nowiki>''. This feature started appearing in early versions of [[Firefox]], when it still had the working title 'Firebird' in early 2003, from an earlier practice in browsers such as [[Lynx (web browser)|Lynx]].<ref>{{cite web |url=http://forums.mozillazine.org/viewtopic.php?f=9&t=10980 |title=automatically adding www.___.com |publisher=mozillaZine |date=16 May 2003 |access-date=27 May 2009 |url-status=live |archive-url=https://web.archive.org/web/20090627225046/http://forums.mozillazine.org/viewtopic.php?f=9&t=10980 |archive-date=27 June 2009}}</ref> {{unreliable source?|date=November 2016}} It is reported that Microsoft was granted a US patent for the same idea in 2008, but only for mobile devices.<ref>{{cite web |url=http://techdirt.com/articles/20080626/0203581527.shtml |title=Microsoft Patents Adding 'www.' And '.com' To Text |publisher=Techdirt |last=Masnick |first=Mike |date=7 July 2008 |access-date=27 May 2009 |url-status=live |archive-url=https://web.archive.org/web/20090627212151/http://www.techdirt.com/articles/20080626/0203581527.shtml |archive-date=27 June 2009}}</ref>

=== Scheme specifiers ===
The scheme specifiers ''<code><nowiki>http://</nowiki></code>'' and ''<code><nowiki>https://</nowiki></code>'' at the start of a web [[Uniform Resource Identifier|URI]] refer to [[Hypertext Transfer Protocol]] or [[HTTP Secure]], respectively. They specify the communication protocol to use for the request and response. The HTTP protocol is fundamental to the operation of the World Wide Web, and the added encryption layer in HTTPS is essential when browsers send or retrieve confidential data, such as passwords or banking information. Web browsers usually automatically prepend <nowiki>http://</nowiki> to user-entered URIs, if omitted.{{Citation needed|date=May 2025}}

===Pages===
{{main|Web page}}
[[File:Commons.png|thumb|A screenshot of the home page of Wikimedia Commons]]
A ''web page'' (also written as ''webpage'') is a document that is suitable for the World Wide Web and [[web browser]]s. A web browser displays a web page on a [[computer display|monitor]] or [[mobile device]].

The term ''web page'' usually refers to what is visible, but may also refer to the contents of the [[computer file]] itself, which is usually a [[text file]] containing [[hypertext]] written in [[HTML]] or a comparable [[markup language]]. Typical web pages provide [[hypertext]] for browsing to other web pages via [[hyperlink]]s, often referred to as ''links''. Web browsers will frequently have to access multiple [[web resource]] elements, such as reading [[Cascading Style Sheets|style sheets]], [[client-side scripting|scripts]], and images, while presenting each web page.

On a network, a web browser can retrieve a web page from a remote [[web server]]. The web server may restrict access to a private network such as a corporate intranet. The web browser uses the [[Hypertext Transfer Protocol]] (HTTP) to make such requests to the [[web server]].

A [[static web page|''static'' web page]] is delivered exactly as stored, as [[web content]] in the web server's [[file system]]. In contrast, a [[dynamic web page|''dynamic'' web page]] is generated by a [[web application]], usually driven by [[server-side scripting|server-side software]]. Dynamic web pages are used when each user may require completely different information, for example, bank websites, web email etc.

==== Static page ====
{{main|Static web page}}
A ''static web page'' (sometimes called a ''flat page/stationary page'') is a [[web page]] that is delivered to the user exactly as stored, in contrast to [[dynamic web page]]s which are generated by a [[web application]].

Consequently, a static web page displays the same information for all users, from all contexts, subject to modern capabilities of a [[web server]] to [[content negotiation|negotiate]] [[MIME type|content-type]] or language of the document where such versions are available and the server is configured to do so.

==== Dynamic pages ====
{{Main|Dynamic web page|Ajax (programming)}}
[[File:Scheme dynamic page en.svg|thumb|right|500px|Dynamic web page: example of server-side scripting ([[PHP]] and [[MySQL]])]]
A ''server-side dynamic web page'' is a [[web page]] whose construction is controlled by an [[application server]] processing server-side scripts. In server-side scripting, [[Parameter (computer programming)|parameters]] determine how the assembly of every new web page proceeds, including the setting up of more client-side processing.

A ''client-side dynamic web page'' processes the web page using JavaScript running in the browser. JavaScript programs can interact with the document via [[Document Object Model]], or DOM, to query page state and alter it. The same client-side techniques can then dynamically update or change the DOM in the same way.

A dynamic web page is then reloaded by the user or by a [[computer program]] to change some variable content. The updating information could come from the server, or from changes made to that page's DOM. This may or may not truncate the browsing history or create a saved version to go back to, but a ''dynamic web page update'' using [[Ajax (programming)|Ajax]] technologies will neither create a page to go back to nor truncate the [[web browsing history]] forward of the displayed page. Using Ajax technologies the end [[User (computing)|user]] gets ''one dynamic page'' managed as a single page in the [[web browser]] while the actual [[web content]] rendered on that page can vary. The Ajax engine sits only on the browser requesting parts of its DOM, ''the'' DOM, for its client, from an application server.

Dynamic HTML, or DHTML, is the umbrella term for technologies and methods used to create web pages that are not [[static web page]]s, though it has fallen out of common use since the popularization of [[Ajax (programming)|AJAX]], a term which is now itself rarely used.{{citation needed|date=March 2021}} Client-side-scripting, server-side scripting, or a combination of these make for the dynamic web experience in a browser.

[[JavaScript]] is a [[scripting programming language|scripting language]] that was initially developed in 1995 by [[Brendan Eich]], then of [[Netscape]], for use within web pages.<ref name=Hamilton>{{cite web|author=Hamilton, Naomi|title=The A-Z of Programming Languages: JavaScript|url=http://computerworld.com.au/article/255293/-z_programming_languages_javascript|date=31 July 2008|work=Computerworld|publisher=IDG|access-date=12 May 2009|url-status=live|archive-url=https://web.archive.org/web/20090524025720/http://www.computerworld.com.au/article/255293/-z_programming_languages_javascript|archive-date=24 May 2009}}</ref> The standardised version is [[ECMAScript]].<ref name=Hamilton /> To make web pages more interactive, some web applications also use JavaScript techniques such as [[Ajax (programming)|Ajax]] ([[Asynchronous I/O|asynchronous]] JavaScript and [[XML]]). [[Client-side scripting|Client-side script]] is delivered with the page that can make additional HTTP requests to the server, either in response to user actions such as mouse movements or clicks, or based on elapsed time. The server's responses are used to modify the current page rather than creating a new page with each response, so the server needs only to provide limited, incremental information. Multiple Ajax requests can be handled at the same time, and users can interact with the page while data is retrieved. Web pages may also regularly [[polling (computer science)|poll]] the server to check whether new information is available.<ref>{{cite web|url=http://buntin.org/2008/sep/23/jquery-polling-plugin/|title=jQuery Polling plugin|date=23 September 2008|last=Buntin|first=Seth|access-date=22 August 2009|url-status=dead|archive-url=https://web.archive.org/web/20090813184848/http://buntin.org/2008/sep/23/jquery-polling-plugin/|archive-date=13 August 2009}}</ref>

===Website===
[[File:United States Antarctic Program website from 2018 02 22.png|thumb|right|240px|The [[United States Antarctic Program|usap.gov]] website]]
{{main|Website}}
A ''website''<ref>{{cite web|url=http://www.thefreedictionary.com/Website|title=website|website=[[TheFreeDictionary.com]]|access-date=2 July 2011|archive-date=7 May 2018|archive-url=https://web.archive.org/web/20180507204408/https://www.thefreedictionary.com/website|url-status=live}}</ref> is a collection of related web resources including [[web page]]s, [[multimedia]] content, typically identified with a common [[domain name]], and published on at least one [[web server]]. Notable examples are [[wikipedia]].org, [[google]].com, and [[Amazon (company)|amazon.com]].

A website may be accessible via a public [[Internet Protocol]] (IP) network, such as the [[Internet]], or a private [[local area network]] (LAN), by referencing a [[URL|uniform resource locator]] (URL) that identifies the site.

Websites can have many functions and can be used in various fashions; a website can be a [[personal website]], a corporate website for a company, a government website, an organization website, etc. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and [[social networking]] to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically a part of an [[intranet]].

Web pages, which are the building blocks of websites, are [[document]]s, typically composed in [[plain text]] interspersed with [[Formatted text|formatting instructions]] of Hypertext Markup Language ([[HTML]], [[XHTML]]). They may incorporate elements from other websites with suitable [[HTML anchor|markup anchors]]. Web pages are accessed and transported with the [[Hypertext Transfer Protocol]] (HTTP), which may optionally employ encryption ([[HTTP Secure]], HTTPS) to provide security and privacy for the user. The user's application, often a [[web browser]], renders the page content according to its HTML markup instructions onto a [[Computer monitor|display terminal]].

[[Hyperlink]]ing between web pages conveys to the reader the [[site map|site structure]] and guides the navigation of the site, which often starts with a [[home page]] containing a directory of the site [[web content]]. Some websites require user registration or [[subscription]] to access content. Examples of [[paywall|subscription websites]] include many business sites, news websites, [[academic journal]] websites, gaming websites, file-sharing websites, [[Internet forum|message boards]], web-based [[email]], [[social networking]] websites, websites providing real-time price quotations for different types of markets, as well as sites providing various other services. [[End user]]s can access websites on a range of devices, including [[desktop computer|desktop]] and [[laptop|laptop computers]], [[tablet computer]]s, [[smartphone]]s and [[smart TV]]s.

===Browser===
{{main|Web browser}}
A ''web browser'' (commonly referred to as a ''browser'') is a [[software application|software]] [[user agent]] for accessing information on the World Wide Web. To connect to a website's [[web server|server]] and display its pages, a user needs to have a web browser program. This is the program that the user runs to download, format, and display a web page on the user's computer.

In addition to allowing users to find, display, and move between web pages, a web browser will usually have features like keeping bookmarks, recording history, managing cookies (see below), and home pages and may have facilities for recording passwords for logging into websites.

The most popular browsers are [[Google Chrome|Chrome]], [[Safari (web browser)|Safari]], [[Microsoft Edge|Edge]], [[Samsung Internet]] and [[Firefox]].<ref>{{Cite web |title=Top Browsers Market Share |url=https://www.similarweb.com/browsers/ |access-date=2025-02-15 |website=www.similarweb.com |archive-date=17 February 2025 |archive-url=https://web.archive.org/web/20250217112440/https://www.similarweb.com/browsers/ |url-status=live }}</ref>

===Server===
{{main|Web server}}

[[File:Inside and Rear of Webserver.jpg|thumb|right|The inside and front of a [[Dell PowerEdge]] web server, a computer designed for [[rack mount]]ing]]
A ''Web server'' is [[server software]], or hardware dedicated to running said software, that can satisfy World Wide Web client requests. A web server can, in general, contain one or more websites. A web server processes incoming network requests over [[Hypertext Transfer Protocol|HTTP]] and several other related protocols.

The primary function of a web server is to store, process and deliver [[web page]]s to [[Client (computing)|clients]].<ref>{{Cite book|title=Web performance tuning|last=Patrick|first=Killelea|date=2002|publisher=O'Reilly|isbn=978-0596001728|edition= 2nd|location=Beijing|pages=264|oclc=49502686}}</ref> The communication between client and server takes place using the [[Hypertext Transfer Protocol|Hypertext Transfer Protocol (HTTP)]]. Pages delivered are most frequently [[HTML|HTML documents]], which may include [[image]]s, [[Style sheet (web development)|style sheets]] and [[JavaScript|scripts]] in addition to the text content.
[[File:Wikimedia Foundation Servers-8055 35.jpg|thumb|275x275px|Multiple web servers may be used for a high traffic website; here, [[Dell]] servers are installed together to be used for the [[Wikimedia Foundation]].]]

A [[user agent]], commonly a [[web browser]] or [[web crawler]], initiates communication by making a [[Hypertext Transfer Protocol#Request message|request]] for a specific resource using HTTP and the server responds with the content of that resource or an [[List of HTTP status codes#4xx client errors|error message]] if unable to do so. The resource is typically a real file on the server's [[secondary memory|secondary storage]], but this is not necessarily the case and depends on how the webserver is [[Implementation|implemented]].

While the primary function is to serve content, full implementation of HTTP also includes ways of receiving content from clients. This feature is used for submitting [[Form (web)|web forms]], including [[upload]]ing of files.

Many generic web servers also support  [[server-side scripting|scripting]] using [[Active Server Pages]] (ASP), [[PHP]] (Hypertext Preprocessor), or other [[scripting language]]s. This means that the behaviour of the webserver can be scripted in separate files, while the actual server software remains unchanged. Usually, this function is used to generate HTML documents [[Dynamic web page|dynamically]] ("on-the-fly") as opposed to returning [[Static web page|static documents]]. The former is primarily used for retrieving or modifying information from [[database]]s. The latter is typically much faster and more easily [[web cache|cached]] but cannot deliver [[dynamic content]].

Web servers can also frequently be found [[embedded system|embedded]] in devices such as [[printer (computing)|printers]], [[Router (computing)|routers]], [[webcam]]s and serving only a [[Local area network|local network]]. The web server may then be used as a part of a system for monitoring or administering the device in question. This usually means that no additional software has to be installed on the client computer since only a web browser is required (which now is included with most [[operating system]]s).

===Optical Networking===
[[Optical networking]] is a sophisticated infrastructure that utilizes optical fiber to transmit data over long distances, connecting countries, cities, and even private residences. The technology uses optical microsystems like [[tunable laser]]s, filters, [[Attenuator (electronics)|attenuators]], switches, and wavelength-selective switches to manage and operate these networks.<ref>{{Cite journal |last=Liu |first=Xiang |date=2019-12-20 |title=Evolution of Fiber-Optic Transmission and Networking toward the 5G Era |journal=iScience |language=English |volume=22 |pages=489–506 |doi=10.1016/j.isci.2019.11.026 |issn=2589-0042 |pmc=6920305 |pmid=31838439|bibcode=2019iSci...22..489L }}</ref><ref>{{Citation |last=Marom |first=Dan M. |title=3.07 - Optical Communications |date=2008-01-01 |work=Comprehensive Microsystems |pages=219–265 |editor-last=Gianchandani |editor-first=Yogesh B. |url=https://linkinghub.elsevier.com/retrieve/pii/B9780444521903000355 |access-date=2025-01-17 |place=Oxford |publisher=Elsevier |doi=10.1016/b978-044452190-3.00035-5 |isbn=978-0-444-52190-3 |editor2-last=Tabata |editor2-first=Osamu |editor3-last=Zappe |editor3-first=Hans |archive-date=23 January 2025 |archive-url=https://web.archive.org/web/20250123163122/https://linkinghub.elsevier.com/retrieve/pii/B9780444521903000355 |url-status=live }}</ref>

The large quantity of optical fiber installed throughout the world at the end of the twentieth century set the foundation of the Internet as it is used today. The information highway relies heavily on optical networking, a method of sending messages encoded in light to relay information in various telecommunication networks.<ref>{{Cite book |last=Chadha |first=Devi |title=Optical WDM networks: from static to elastic networks |date=2019 |publisher=Wiley-IEEE Press |isbn=978-1-119-39326-9 |location=Hoboken, NJ}}</ref>

The [[ARPANET|Advanced Research Projects Agency Network]] (ARPANET) was one of the first iterations of the Internet, created in collaboration with universities and researchers 1969.<ref>{{Cite web |date=2019-03-29 |title=The Computer History Museum, SRI International, and BBN Celebrate the 40th Anniversary of First ARPANET Transmission, Precursor to Today's Internet {{!}} SRI International |url=https://www.sri.com/newsroom/press-releases/computer-history-museum-sri-international-and-bbn-celebrate-40th-anniversary |access-date=2025-01-21 |archive-url=https://web.archive.org/web/20190329134941/https://www.sri.com/newsroom/press-releases/computer-history-museum-sri-international-and-bbn-celebrate-40th-anniversary |archive-date=29 March 2019 |url-status=dead }}</ref><ref>{{Cite news |last=Markoff |first=John |date=1993-01-24 |title=Building the Electronic Superhighway |url=https://www.nytimes.com/1993/01/24/business/building-the-electronic-superhighway.html |access-date=2025-01-21 |work=The New York Times |language=en-US |issn=0362-4331}}</ref><ref>{{Cite book |last=Abbate |first=Janet |title=Inventing the Internet |date=2000 |publisher=MIT Press |isbn=978-0-262-51115-5 |edition=3rd printing |series=Inside technology |location=Cambridge, Mass.}}</ref><ref name=":0">{{Cite web |title=NSFNET: A Partnership for High-Speed Networking |url=http://www.merit.edu/wp-content/uploads/2019/06/NSFNET_final-1.pdf |archive-url=https://web.archive.org/web/20241106150721/https://www.merit.edu/wp-content/uploads/2019/06/NSFNET_final-1.pdf |archive-date=6 November 2024 |access-date=2025-01-21 |website=www.merit.edu |url-status=live }}</ref> However, access to the ARPANET was limited to researchers, and in 1985, the [[National Science Foundation]] founded the [[National Science Foundation Network]] (NSFNET), a program that provided supercomputer access to researchers.<ref name=":0" />

Limited public access to the Internet led to pressure from consumers and corporations to privatize the network. In 1993, the US passed the [[National Information Infrastructure|National Information Infrastructure Act]], which dictated that the National Science Foundation must hand over control of the optical capabilities to commercial operators.<ref>{{Cite web |last=Rep. Boucher |first=Rick [D-VA-9 |date=1993-09-14 |title=H.R.1757 - 103rd Congress (1993-1994): National Information Infrastructure Act of 1993 |url=https://www.congress.gov/bill/103rd-congress/house-bill/1757 |access-date=2025-01-23 |website=www.congress.gov |archive-date=10 November 2021 |archive-url=https://web.archive.org/web/20211110001120/https://www.congress.gov/bill/103rd-congress/house-bill/1757 |url-status=live }}</ref><ref>{{Cite web |date=2003-07-25 |title=NSF Shapes the Internet's Evolution {{!}} NSF - National Science Foundation |url=https://new.nsf.gov/news/nsf-shapes-internets-evolution |access-date=2025-01-23 |website=new.nsf.gov |language=en}}</ref>

The privatization of the Internet and the release of the World Wide Web to the public in 1993 led to an increased demand for Internet capabilities. This spurred developers to seek solutions to reduce the time and cost of laying new fiber and increase the amount of information that can be sent on a single fiber, in order to meet the growing needs of the public.<ref>{{Citation |last=Radu |first=Roxana |title=Privatization and Globalization of the Internet |date=2019-03-07 |work=Negotiating Internet Governance |pages=75–112 |editor-last=Radu |editor-first=Roxana |url=https://academic.oup.com/book/35243/chapter/299787096 |access-date=2025-01-23 |publisher=Oxford University Press |doi=10.1093/oso/9780198833079.003.0004 |isbn=978-0-19-883307-9 |archive-date=14 February 2025 |archive-url=https://web.archive.org/web/20250214121234/https://academic.oup.com/book/35243/chapter/299787096 |url-status=live }}</ref><ref>{{Cite web |title=Birth of the Commercial Internet - NSF Impacts {{!}} NSF - National Science Foundation |url=https://new.nsf.gov/impacts/internet#:~:text=Going%20public,dedicated%20infrastructure%20backbone%20in%201995 |access-date=2025-01-23 |website=new.nsf.gov |language=en}}</ref><ref>{{Cite news |last=Markoff |first=John |date=1997-03-03 |title=Fiber-Optic Technology Draws Record Stock Value |url=https://www.nytimes.com/1997/03/03/business/fiber-optic-technology-draws-record-stock-value.html |access-date=2025-01-23 |work=The New York Times |language=en-US |issn=0362-4331 |archive-date=9 October 2019 |archive-url=https://web.archive.org/web/20191009170252/https://www.nytimes.com/1997/03/03/business/fiber-optic-technology-draws-record-stock-value.html |url-status=live }}</ref><ref>Paul Korzeniowski, [https://www.proquest.com/trade-journals/record-growth-spurs-demand-dense-wdm/docview/226891627/se-2?accountid=44910 “Record Growth Spurs Demand for Dense WDM -- Infrastructure Bandwidth Gears up for next Wave,”] CommunicationsWeek, no. 666 (June 2, 1997): T.40.</ref>

In 1994, Pirelli S.p.A.'s optical components division introduced a wavelength-division multiplexing (WDM) system to meet growing demand for increased data transmission. This four-channel WDM technology allowed more information to be sent simultaneously over a single optical fiber, effectively boosting network capacity.<ref>{{Cite book |last=Hecht |first=Jeff |title=City of light: the story of fiber optics |date=1999 |publisher=Oxford University Press |isbn=978-0-19-510818-7 |series=The Sloan technology series |location=New York}}</ref><ref>{{Cite web |title=Cisco to Acquire Pirelli DWDM Unit for $2.15 Billion |url=https://www.fiberopticsonline.com/doc/cisco-to-acquire-pirelli-dwdm-unit-for-215-bi-0001 |access-date=2025-01-31 |website=www.fiberopticsonline.com}}</ref>

Pirelli wasn't the only company that developed a WDM system; another company, the [[Ciena|Ciena Corporation]] (Ciena), created its own technology to transmit data more efficiently. [[David R. Huber|David Huber]], an optical networking engineer and entrepreneur [[Kevin Kimberlin]] founded Ciena in 1992.<ref>Hirsch, Stacey (February 2, 2006). "Huber steps down as CEO of Broadwing". The Baltimore Sun.</ref><ref>{{Cite web |title=Dr. David Huber |url=https://internethistory.org/bio/dr-david-huber/ |access-date=2025-02-03 |website=History of the Internet |language=en-US}}</ref><ref>{{Cite web |title=Internet Commercialization History |url=https://internethistory.org/commercialization/ |access-date=2025-02-03 |website=History of the Internet |language=en-US}}</ref> Drawing on laser technology from [[Gordon Gould]] and William Culver of [[Optelecom|Optelecom, Inc.]], the company focused on utilizing optical amplifiers to transmit data via light.<ref>{{Cite web |title=May 17, 1993, page 76 - The Baltimore Sun at Baltimore Sun |url=https://baltimoresun.newspapers.com/article/the-baltimore-sun-the-sun-business/170638608/ |access-date=2025-02-03 |website=Newspapers.com |language=en |archive-date=21 February 2025 |archive-url=https://web.archive.org/web/20250221021809/https://baltimoresun.newspapers.com/image/170916535/ |url-status=live }}</ref><ref>Hall, Carla. [http://www.latimes.com/archives/la-xpm-1987-12-17-vw-29544-story.html “Inventor Beams over Laser Patents : After 30 Years, Gordon Gould Gets Credit He Deserves.”] Los Angeles Times, Los Angeles Times, 17 Dec. 1987.</ref><ref>{{Cite news |last=Chang |first=Kenneth |date=2005-09-20 |title=Gordon Gould, 85, Figure in Invention of the Laser, Dies |url=https://www.nytimes.com/2005/09/20/science/gordon-gould-85-figure-in-invention-of-the-laser-dies.html |access-date=2025-02-03 |work=The New York Times |language=en-US |issn=0362-4331 |archive-date=19 September 2017 |archive-url=https://web.archive.org/web/20170919230151/http://www.nytimes.com/2005/09/20/science/gordon-gould-85-figure-in-invention-of-the-laser-dies.html |url-status=live }}</ref> Under chief executive officer Pat Nettles, Ciena developed a dual-stage optical amplifier for dense wavelength-division multiplexing (DWDM), patented in 1997 and deployed on the Sprint network in 1996.<ref>{{Cite web |last=Carroll |first=Jim |date=2024-12-12 |title=Patrick Nettles Steps Down as Executive Chair of Ciena |url=https://convergedigest.com/patrick-nettles-steps-down-as-executive-chair-of-ciena/ |access-date=2025-02-03 |website=Converge Digest |language=en-US |archive-date=14 February 2025 |archive-url=https://web.archive.org/web/20250214112552/https://convergedigest.com/patrick-nettles-steps-down-as-executive-chair-of-ciena/ |url-status=live }}</ref><ref>{{Cite patent|number=US5696615A|title=Wavelength division multiplexed optical communication systems employing uniform gain optical amplifiers|gdate=1997-12-09|invent1=Alexander|inventor1-first=Stephen B.|url=https://patents.google.com/patent/US5696615A/en}}</ref><ref>{{Cite book |last=Hecht |first=Jeff |title=City of light: the story of fiber optics |date=2004 |publisher=Oxford Univ. Press |isbn=978-0-19-510818-7 |edition=Rev. and expanded ed., 1. paperback [ed.] |series=The Sloan technology series |location=Oxford}}</ref><ref>{{Cite web |title=Optica Publishing Group |url=https://opg.optica.org/oe/viewmedia.cfm?uri=oe-26-18-24190&html=true |access-date=2025-02-03 |website=opg.optica.org |archive-date=26 January 2025 |archive-url=https://web.archive.org/web/20250126182827/https://opg.optica.org/oe/viewmedia.cfm?uri=oe-26-18-24190&html=true |url-status=live }}</ref><ref>{{Cite web |title=Sprint boots some users off 'Net - ProQuest |url=https://www.proquest.com/docview/215944575 |access-date=2025-02-03 |website=www.proquest.com | id={{ProQuest|215944575}} |language=en}}</ref>

===Cookie===
{{main|HTTP cookie}}
An ''HTTP cookie'' (also called ''web cookie'', ''Internet cookie'', ''browser cookie'', or simply ''cookie'') is a small piece of data sent from a website and stored on the user's computer by the user's [[web browser]] while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember [[program state|stateful]] information (such as items added in the shopping cart in an online store) or to record the user's browsing activity (including clicking particular buttons, [[access control|logging in]], or recording which pages were visited in the past). They can also be used to remember arbitrary pieces of information that the user previously entered into form fields such as names, addresses, passwords, and credit card numbers.

Cookies perform essential functions in the modern web. Perhaps most importantly, ''authentication cookies'' are the most common method used by web servers to know whether the user is logged in or not, and which account they are logged in with. Without such a mechanism, the site would not know whether to send a page containing sensitive information or require the user to authenticate themselves by logging in. The security of an authentication cookie generally depends on the security of the issuing website and the user's [[comparison of web browsers#Vulnerabilities|web browser]], and on whether the cookie data is encrypted. Security vulnerabilities may allow a cookie's data to be read by a [[hacker (computer security)|hacker]], used to gain access to user data, or used to gain access (with the user's credentials) to the website to which the cookie belongs (see [[cross-site scripting]] and [[cross-site request forgery]] for examples).<ref>{{cite web |url=http://news.cnet.com/8301-10789_3-9918582-57.html |first=Robert |last=Vamosi |title=Gmail cookie stolen via Google Spreadsheets |website=News.cnet.com |date=14 April 2008 |access-date=19 October 2017 |archive-date=9 December 2013 |archive-url=https://web.archive.org/web/20131209210402/http://news.cnet.com/8301-10789_3-9918582-57.html |url-status=dead }}</ref>

Tracking cookies, and especially third-party tracking cookies, are commonly used as ways to compile long-term records of individuals' browsing histories {{En dash}} a potential [[Internet privacy#HTTP cookies|privacy concern]] that prompted European<ref>{{cite web |title=What about the "EU Cookie Directive"? |url=http://webcookies.org/faq/#Directive |year=2013 |publisher=WebCookies.org |access-date=19 October 2017 |archive-date=11 October 2017 |archive-url=https://web.archive.org/web/20171011095259/https://webcookies.org/faq/#Directive |url-status=dead }}</ref> and U.S. lawmakers to take action in 2011.<ref name="eulaw">{{cite news |url=https://www.bbc.co.uk/news/technology-12668552 |work=BBC |title=New net rules set to make cookies crumble |date=8 March 2011 |access-date=18 February 2019 |archive-date=10 August 2018 |archive-url=https://web.archive.org/web/20180810220427/https://www.bbc.co.uk/news/technology-12668552 |url-status=live }}</ref><ref>{{cite web |url=http://adage.com/article/digital/sen-rockefeller-ready-a-real-track-bill/227426/ |work=Adage.com |title=Sen. Rockefeller: Get Ready for a Real Do-Not-Track Bill for Online Advertising |date=6 May 2011 |access-date=18 February 2019 |archive-date=24 August 2011 |archive-url=https://web.archive.org/web/20110824225528/http://adage.com/article/digital/sen-rockefeller-ready-a-real-track-bill/227426/ |url-status=live }}</ref> European law requires that all websites targeting [[European Union]] member states gain "informed consent" from users before storing non-essential cookies on their device.

Google [[Project Zero (Google)|Project Zero]] researcher Jann Horn describes ways cookies can be read by [[Man-in-the-middle attack|intermediaries]], like [[Wi-Fi]] hotspot providers. When in such circumstances, he recommends using the browser in [[private browsing]] mode (widely known as [[Incognito mode]] in Google Chrome).<ref>[https://thejh.net/written-stuff/want-to-use-my-wifi? Want to use my wifi?] {{Webarchive|url=https://web.archive.org/web/20180104070103/https://thejh.net/written-stuff/want-to-use-my-wifi |date=4 January 2018 }}, Jann Horn accessed 5 January 2018.</ref>

===Search engine===
{{main|Search engine}}
[[File:Mayflower Wikimedia Commons image search engine screenshot.png|thumb|upright=1.35|The results of a search for the term "lunar eclipse" in a web-based [[image search]] engine]]
A ''web search engine'' or ''Internet search engine'' is a [[software system]] that is designed to carry out ''web search'' (''Internet search''), which means to search the World Wide Web in a systematic way for particular information specified in a [[web search query]]. The search results are generally presented in a line of results, often referred to as [[search engine results page]]s (SERPs). The information may be a mix of [[web page]]s, images, videos, infographics, articles, research papers, and other types of files. Some search engines also [[data mining|mine data]] available in [[database]]s or [[web directory|open directories]]. Unlike [[web directories]], which are maintained only by human editors, search engines also maintain [[real-time computing|real-time]] information by running an [[algorithm]] on a [[web crawler]]. Internet content that is not capable of being searched by a web search engine is generally described as the [[deep web]].

In 1990, [[Archie (search engine)|Archie]], the world's first search engine, was released. The technology was originally an index of [[File Transfer Protocol]] (FTP) sites, which was a method for moving files between a client and a server network.<ref>{{Cite web |last=Nguyen |first=Jennimai |date=2020-09-10 |title=Archie, the very first search engine, was released 30 years ago today |url=https://mashable.com/article/first-search-engine-archie?test_uuid=01iI2GpryXngy77uIpA3Y4B&test_variant=b |access-date=2025-02-04 |website=Mashable |language=en}}</ref><ref>{{Cite web |title=What is File Transfer Protocol (FTP) meaning |url=https://www.fortinet.com/resources/cyberglossary/file-transfer-protocol-ftp-meaning |access-date=2025-02-04 |website=Fortinet |language=en |archive-date=26 January 2025 |archive-url=https://web.archive.org/web/20250126193905/https://www.fortinet.com/resources/cyberglossary/file-transfer-protocol-ftp-meaning |url-status=live }}</ref> This early search tool was superseded by more advanced engines like [[Yahoo!]] in 1995 and [[Google Search|Google]] in 1998.<ref>{{Cite web |date=2025-02-04 |title=Britannica Money |url=https://money.britannica.com/money/Google-Inc |access-date=2025-02-04 |website=www.britannica.com |language=en |archive-date=27 July 2024 |archive-url=https://web.archive.org/web/20240727122207/https://money.britannica.com/money/Google-Inc |url-status=live }}</ref><ref>{{Cite news |last=Clark |first=Andrew |date=2008-02-01 |title=How Jerry's guide to the world wide web became Yahoo |url=https://www.theguardian.com/business/2008/feb/01/microsoft.technology |access-date=2025-02-04 |work=The Guardian |language=en-GB |issn=0261-3077 |archive-date=5 October 2013 |archive-url=https://web.archive.org/web/20131005052548/http://www.theguardian.com/business/2008/feb/01/microsoft.technology |url-status=live }}</ref>

===Deep web===
{{Multiple image
| image1            = Deep web diagram.png
| caption1          = Deep web diagram
| width1            = 1400
| image2            = Deep web vs surface web.svg
| caption2          = Deep web vs surface web
| width2            = 1400
| image3            = Surface Web & Deep Web.jpg
| width3            = 1400
| caption3          = Surface Web & Deep Web
| total_width       = 230
| direction         = vertical
}}
{{main|Deep web}}
The deep web,<ref name="nhamilton">{{cite journal|url=https://www.iadisportal.org/digital-library/the-mechanics-of-a-deep-net-metasearch-engine|journal=IADIS Digital Library|title=The Mechanics of a Deep Net Metasearch Engine|last=Hamilton|first=Nigel|date=13 May 2024|pages=1034–1036|isbn=978-972-98947-0-1|archive-date=31 May 2023|access-date=6 May 2024|archive-url=https://web.archive.org/web/20230531071443/https://www.iadisportal.org/digital-library/the-mechanics-of-a-deep-net-metasearch-engine|url-status=live}}</ref> ''invisible web'',<ref name="jal">{{cite journal|title=Beyond google: the invisible web in the academic library |volume=30|issue=4|date=July 2004|pages=265–269|last1=Devine|first1=Jane|last2=Egger-Sider|first2=Francine|journal=The Journal of Academic Librarianship |doi=10.1016/j.acalib.2004.04.010 }}</ref> or ''hidden web''<ref name="cthw">{{cite journal|title=Crawling the Hidden Web|journal=27th International Conference on Very Large Data Bases|date=11–14 September 2001|first1=Sriram|last1=Raghavan|first2=Hector|last2=Garcia-Molina|url=http://ilpubs.stanford.edu:8090/725/|access-date=18 February 2019|archive-date=17 August 2019|archive-url=https://web.archive.org/web/20190817174115/http://ilpubs.stanford.edu:8090/725/|url-status=live}}</ref> are parts of the World Wide Web whose contents are not [[Search engine indexing|indexed]] by standard [[web search engine]]s. The opposite term to the deep web is the [[surface web]], which is accessible to anyone using the Internet.<ref>{{cite web |title=Surface Web |url=https://www.computerhope.com/jargon/s/surface-web.htm |publisher=Computer Hope |access-date=20 June 2018 |archive-date=5 May 2020 |archive-url=https://web.archive.org/web/20200505062819/https://www.computerhope.com/jargon/s/surface-web.htm |url-status=live }}</ref> [[Computer scientist]] Michael K. Bergman is credited with coining the term ''deep web'' in 2001 as a search indexing term.<ref name="wright2009"/>

The content of the deep web is hidden behind [[HTTP]] forms,<ref>Madhavan, J., Ko, D., Kot, Ł., Ganapathy, V., Rasmussen, A., & Halevy, A. (2008). Google's deep web crawl. Proceedings of the VLDB Endowment, 1(2), 1241–52.</ref><ref>{{cite web|url=https://www.questia.com/article/1G1-370513892/how-do-you-want-me-to-do-it-does-it-have-to-look|title=How Do You Want Me to Do It? Does It Have to Look like an Accident? – an Assassin Selling a Hit on the Net; Revealed Inside the Deep Web|url-access=subscription|via=|newspaper=[[Sunday Mail (Scotland)|Sunday Mail]]|date=8 June 2014|first=Sam|last=Shedden|access-date=5 May 2017|archive-date=1 March 2020|archive-url=https://web.archive.org/web/20200301174912/https://www.questia.com/article/1G1-370513892/how-do-you-want-me-to-do-it-does-it-have-to-look|url-status=dead}}</ref> and includes many very common uses such as [[web mail]], [[online banking]], and services that users must pay for, and which is protected by a [[paywall]], such as [[video on demand]], some online magazines and newspapers, among others.

The content of the deep web can be located and accessed by a direct [[URL]] or [[IP address]] and may require a password or other security access past the public website page.

=== Caching ===
A [[web cache]] is a server computer located either on the public Internet or within an enterprise that stores recently accessed web pages to improve response time for users when the same content is requested within a certain time after the original request. Most web browsers also implement a [[browser cache]] by writing recently obtained data to a local data storage device. HTTP requests by a browser may ask only for data that has changed since the last access. Web pages and resources may contain expiration information to control caching to secure sensitive data, such as in [[online banking]], or to facilitate frequently updated sites, such as news media. Even sites with highly dynamic content may permit basic resources to be refreshed only occasionally. Web site designers find it worthwhile to collate resources such as CSS data and JavaScript into a few site-wide files so that they can be cached efficiently. Enterprise [[Firewall (networking)|firewalls]] often cache Web resources requested by one user for the benefit of many users. Some [[search engines]] store cached content of frequently accessed websites.