Editing Physical layer (section)

== Role ==
The physical layer defines the means of transmitting a stream of raw [[bit]]s<ref>{{cite web |url=http://www.erg.abdn.ac.uk/users/gorry/course/phy-pages/phy.html |archive-url=https://web.archive.org/web/20090618154921/http://www.erg.abdn.ac.uk/users/gorry/course/phy-pages/phy.html |archive-date=2009-06-18 |title=Physical Layer |author=Gorry Fairhurst |date=2001-01-01}}</ref> over a physical [[data link]] connecting [[network node]]s. The [[bitstream]] may be grouped into code words or symbols and converted to a physical [[signal]] that is transmitted over a [[transmission medium]]. 

The physical layer consists of the [[electronic circuit]] transmission technologies of a network.<ref name="Fundamentals of Sensor Network Programming">{{cite book | last = Iyengar | first = Shisharama | title = Fundamentals of Sensor Network Programming | publisher = Wiley | year = 2010 | pages = 136 | isbn = 978-1423902454 | url = https://books.google.com/books?id=UD0h_GqgbHgC&q=network%2B+guide+to+networks}}</ref> It is a fundamental layer underlying the higher level functions in a network, and can be implemented through a great number of different hardware technologies with widely varying characteristics.<ref>{{Cite news|url=https://interworks.com/blog/bfair/2011/07/30/physical-layer/|title=The Physical Layer {{!}} InterWorks|date=2011-07-30|work=InterWorks|access-date=2018-08-14|language=en-US}}</ref>

Within the semantics of the OSI model, the physical layer translates logical communications requests from the [[data link layer]] into hardware-specific operations to cause transmission or reception of electronic (or other) signals.<ref>{{Cite web|url=https://www.networkworld.com/article/3239677/lan-wan/the-osi-model-explained-how-to-understand-and-remember-the-7-layer-network-model.html|archive-url=https://web.archive.org/web/20171204233851/https://www.networkworld.com/article/3239677/lan-wan/the-osi-model-explained-how-to-understand-and-remember-the-7-layer-network-model.html|url-status=dead|archive-date=December 4, 2017|title=The OSI model explained: How to understand (and remember) the 7 layer network model|last=Shaw|first=Keith|date=2018-10-22|website=Network World|language=en|access-date=2019-02-15}}</ref><ref>{{Cite web|url=https://www.researchgate.net/publication/288180515|title=DATA COMMUNICATION & NETWORKING|website=ResearchGate|language=en|access-date=2019-02-15}}</ref> The physical layer supports higher layers responsible for generation of logical [[data packet]]s.