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{{Use American English|date=July 2023}}
In [[computing]], '''bandwidth''' is the maximum rate of data transfer across a given path. Bandwidth may be characterized as '''network bandwidth''',<ref>[[Douglas Comer]], [https://books.google.com/books?id=tm-evHmOs3oC&dq=%22network+bandwidth%22+%22computer+networks%22&pg=PA99 Computer Networks and Internets], page 99 ff, Prentice Hall 2008.</ref> '''data bandwidth''',<ref>Fred Halsall, [https://books.google.com/books?id=HrXbAAAAMAAJ&q=%100data+bandwidth%100+Introduction to data+communications and computer networks], page 108, Addison-Wesley, 1985.</ref> or '''digital bandwidth'''.<ref>[https://books.google.com/books?id=7gqsZmr5HJcC&q=+0digital+bandwidth+0+%22 Cisco Networking Academy Program: CCNA 1 and 2 companion guide, Volym 1–2], Cisco Academy 2003</ref><ref>Behrouz A. Forouzan, ''Data communications and networking'', McGraw-Hill, 2007</ref>
This definition of ''bandwidth'' is in contrast to the field of [[signal processing]], [[wireless communications]], [[Modem|modem data transmission]], [[digital communications]], and [[electronics]],{{citation needed|date=January 2018}} in which ''bandwidth'' is used to refer to
==Network capacity==
The term ''bandwidth'' sometimes defines the [[net bit rate]]
==Network consumption==
The ''consumed bandwidth'' in bit/s, corresponds to achieved [[throughput]] or [[goodput]], i.e., the average rate of successful data transfer through a communication path. The consumed bandwidth can be affected by technologies such as [[bandwidth shaping]], [[bandwidth management]], [[bandwidth throttling]], [[bandwidth cap]], [[bandwidth allocation]] (for example [[bandwidth allocation protocol]] and [[dynamic bandwidth allocation]]), etc. A bit stream's bandwidth is proportional to the average consumed signal bandwidth in hertz (the average spectral bandwidth of the analog signal representing the bit stream) during a studied time interval.
''Channel bandwidth'' may be confused with useful data throughput (or goodput). For example, a channel with ''x'' bit/s may not necessarily transmit data at ''x'' rate, since protocols, encryption, and other factors can add appreciable overhead. For instance, much internet traffic uses the [[transmission control protocol]] (TCP), which requires a [[three-way handshake]] for each transaction. Although in many modern implementations the protocol is efficient, it does add significant overhead compared to simpler protocols. Also, data packets may be lost, which further reduces the useful data throughput. In general, for any effective digital communication, a framing protocol is needed; overhead and effective throughput depends on implementation. Useful throughput is less than or equal to the actual channel capacity minus implementation overhead.
==Maximum throughput==
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Digital bandwidth may also refer to: [[bit rate#Multimedia|multimedia bit rate]] or [[average bitrate]] after multimedia [[data compression]] ([[source coding]]), defined as the total amount of data divided by the playback time.
Due to the impractically high bandwidth requirements of uncompressed [[digital media]], the required multimedia bandwidth can be significantly reduced with data compression.<ref name="Lee">{{cite book |last1=Lee |first1=Jack |title=Scalable Continuous Media Streaming Systems: Architecture, Design, Analysis and Implementation |date=2005 |publisher=[[John Wiley & Sons]] |isbn=9780470857649 |page=25 |url=https://books.google.com/books?id=7fuvu52cyNEC&pg=PA25}}</ref> The most widely used data compression technique for media bandwidth reduction is the [[discrete cosine transform]] (DCT), which was first proposed by [[
== Web hosting ==
In [[Web hosting service]], the term ''bandwidth'' is often used to describe the amount of data transferred to or from the website or server within a prescribed period of time, for example ''bandwidth consumption accumulated over a month'' measured in gigabytes per month.{{citation needed|date=November 2011}}<ref>{{Cite web |last=Low |first=Jerry |title=How Much Hosting Bandwidth Do I Need For My Website? |url=https://www.webhostingsecretrevealed.net/blog/web-hosting-guides/how-much-bandwidth-does-your-site-really-need/ |website=WHSR|date=27 March 2022 }}</ref> The more accurate phrase used for this meaning of a maximum amount of data transfer each month or given period is ''monthly data transfer''.{{Citation needed|date=May 2025}}
A similar situation can occur for end-user [[Internet service provider]]s as well, especially where network capacity is limited (for example in areas with underdeveloped internet connectivity and on wireless networks).
== Internet connections ==
{{see also|List of interface bit rates|Bit rate#Progress trends}}
{| class="wikitable"
|+Maximum physical layer net bandwidth of common Internet access technologies
!Bit rate
!Connection type
|-
|56 kbit/s
|[[Dialup]]
|-
|1.5 Mbit/s
|[[ADSL Lite]]
|-
|1.544 Mbit/s
|[[Digital Signal 1|T1/DS1]]
|-
|2.048 Mbit/s
|E1 / [[E-carrier]]
|-
|4 Mbit/s
|[[ADSL1]]
|-
|10 Mbit/s
|[[Ethernet]]
|-
|11 Mbit/s
|Wireless [[802.11b]]
|-
|24 Mbit/s
|[[ADSL2+]]
|-
|44.736 Mbit/s
|[[Digital Signal 3|T3/DS3]]
|-
|54 Mbit/s
|Wireless [[802.11g]]
|-
|100 Mbit/s
|[[Fast Ethernet]]
|-
|155 Mbit/s
|[[OC3]]
|-
|600 Mbit/s
|Wireless [[802.11n]]
|-
|622 Mbit/s
|[[OC12]]
|-
|1 Gbit/s
|[[Gigabit Ethernet]]
|-
|1.3 Gbit/s
|Wireless [[802.11ac]]
|-
|2.5 Gbit/s
|[[OC48]]
|-
|5 Gbit/s
|[[USB 3.2|SuperSpeed USB]]
|-
|7 Gbit/s
|Wireless [[802.11ad]]
|-
|9.6 Gbit/s
|[[OC192]]
|-
|10 Gbit/s
|[[10 Gigabit Ethernet]], [[USB 3.2|SuperSpeed USB 10 Gbit/s]]
|-
|20 Gbit/s
|[[USB 3.2|SuperSpeed USB 20 Gbit/s]]
|-
|40 Gbit/s
|[[Thunderbolt 3]]
|-
|100 Gbit/s
|[[100 Gigabit Ethernet]]
|}
==Edholm's law==
{{Main|Edholm's law}}
The [[MOSFET]] (metal–oxide–semiconductor field-effect transistor) is the most important factor enabling the rapid increase in bandwidth.<ref name="Jindal">{{cite book |last1=Jindal |first1=Renuka P. |title=2009 2nd International Workshop on Electron Devices and Semiconductor Technology |chapter=From millibits to terabits per second and beyond - over 60 years of innovation |date=2009 |pages=1–6 |doi=10.1109/EDST.2009.5166093 |chapter-url=https://events.vtools.ieee.org/m/195547|isbn=978-1-4244-3831-0 |s2cid=25112828 }}</ref> The MOSFET (MOS transistor) was invented by [[Mohamed M. Atalla]] and [[Dawon Kahng]] at [[Bell Labs]] in 1959,<ref name="computerhistory">{{cite journal|url=https://www.computerhistory.org/siliconengine/metal-oxide-semiconductor-mos-transistor-demonstrated/|title=1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated|journal=The Silicon Engine|publisher=[[Computer History Museum]]}}</ref><ref name="Lojek">{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=[[Springer Science & Business Media]] |isbn=9783540342588 |pages=321–3}}</ref><ref name="computerhistory-transistor">{{cite web |title=Who Invented the Transistor? |url=https://www.computerhistory.org/atchm/who-invented-the-transistor/ |website=[[Computer History Museum]] |date=4 December 2013 |access-date=20 July 2019}}</ref> and went on to become the basic building block of modern [[telecommunications]] technology.<ref name="triumph">{{cite web |title=Triumph of the MOS Transistor |url=https://www.youtube.com/watch?v=q6fBEjf9WPw | archive-url=https://ghostarchive.org/varchive/youtube/20211107/q6fBEjf9WPw| archive-date=2021-11-07 | url-status=live|website=[[YouTube]] |publisher=[[Computer History Museum]] |access-date=21 July 2019 |date=6 August 2010}}{{cbignore}}</ref><ref name="Raymer">{{cite book |last1=Raymer |first1=Michael G. |title=The Silicon Web: Physics for the Internet Age |date=2009 |publisher=[[CRC Press]] |isbn=9781439803127 |page=365 |url=https://books.google.com/books?id=PLYChGDqa6EC&pg=PA365}}</ref> Continuous [[MOSFET scaling]], along with various advances in MOS technology, has enabled both [[Moore's law]] ([[transistor count]]s in [[integrated circuit]] chips doubling every two years) and Edholm's law (communication bandwidth doubling every 18 months).<ref name="Jindal"/>
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