Editing Pop-up ad (section)

==Techniques==

==="Pop-ups"===
* Certain types of downloaded content, such as images, free music, and others, can cause pop-ups, and therefore should not be trusted, especially pornographic sites' pop-ups (known as a "pornado" or "porn-storm", as coined by [[John C. Dvorak]].)<ref>{{cite web|url=https://www.pcmag.com/article2/0,2817,1896410,00.asp|title=Ubiquitous Porn: Alive on the Net|work=PCMAG|access-date=21 January 2015}}</ref> Also, the pop-ups sometimes look like ordinary web pages, and the name of the site shows up in a search bar. 
* Many websites use pop-ups to display information without disrupting the page currently open. For example, they may provide needed extra guidance when filling in a [[webform|form]] on a web page, without causing the loss of any information already entered into the form. Most pop-up blockers allow this kind of pop-up. Some, however, reload the page, losing any information the user entered.
* Some online shops use [[Exit intent popup|exit intent popups]], for example offering discounts, in an attempt to retain users.<ref>{{cite web | url=https://blog.useproof.com/exit-intent-popup | title=19 Exit Intent Popup Examples to Increase Conversions in 2022 }}</ref>
* Some web based installers, such as that used by [[McAfee]], use a pop-up to install software.
* On many web browsers, holding down the [[Control key|ctrl]] key while clicking a link makes it bypass the popup filter.<ref>{{cite web|title=How to disable popup-blockers|url=http://de.usa.edu/HowTo/How2PopupBlockers.html|access-date=2013-08-08|archive-url=https://archive.today/20130808091555/http://de.usa.edu/HowTo/How2PopupBlockers.html|archive-date=2013-08-08|url-status=dead}}</ref> 
* Clicking (even accidentally) on one pop-up may open other pop-up ads.

===Pop-under ads===
Pop-under ads are similar to pop-up ads, but the ad window appears hidden behind the main browser window rather than superimposed in front of it. As pop-up ads became more widespread and intrusive, often taking up the whole computer screen, many users would immediately close the pop-up ads that appeared over a site without looking at them. Pop-under ads do not immediately impede the view of content, but remain unnoticed until the user closes or minimizes the main browser window. 

====Pop-under ad technology====
A pop-under ad involves two JavaScript functions introduced in 1995 with the Netscape 2.0b3 browser. Modern web publishers and advertisers use it to create a window in front of the user's screen, load an advertisement, and then send it behind the screen.

<syntaxhighlight lang="javascript">
// create a new window in front of the current site
window.open(URL, windowName[, windowFeatures]); 
// push the loaded advertisement back behind the browser
window.focus();
</syntaxhighlight>

Most modern browsers allow <code>window.open</code> to execute only if it was called by a user interaction (e.g., a mouse click) [[event handler]]. Any non-interactive calls (timer callback, load events, etc.) to <code>window.open</code> result in the new window being blocked.

To bypass this restriction, most pop-under ads trigger on a mouse click event listener attached directly to the document or the document's body. This enables catching all mouse click events that were not consumed by other click event handlers, and calling <code>window.open</code> without being blocked. For example, when the user selects a text, the mouse click triggers the mouse click handler attached to the document and a pop-under opens using the above code. Other techniques to bypass the <code>window.open</code> call restriction do so by "hijacking" mouse clicks.

===Hover ad===

Hover ads, more commonly called in-page pop-ups, are a special type of pop-up ads created using [[Dynamic HTML]], [[JavaScript]] and similar [[web browser]] technologies. Because they do not scroll with the web page, they appear to "hover" over the page, usually obscuring the content. Hover ads tend to be very hard to block by pop-up blocking software, because the hover ad window is an integral part of the HTML content of the web page. Thus software filtering the content has no algorithmic means of recognizing and removing parts of
the content, either descriptive or procedural, that create, populate and manipulate the hover ad's window.