User agent

user-agentuser agent stringuser agentsagentuser agent spoofinguser-agent stringagentsbrowserbrowser ("user agent") detectionbrowsers
In computing, a user agent is software (a software agent) that is acting on behalf of a user.wikipedia
174 Related Articles

Software agent

agentagentssoftware agents
In computing, a user agent is software (a software agent) that is acting on behalf of a user.
User agent - for browsing the World Wide Web

Hypertext Transfer Protocol

HTTPGETrequest
In particular, the Hypertext Transfer Protocol (HTTP) identifies the client software originating the request, using a user-agent header, even when the client is not operated by a user.
A web browser is an example of a user agent (UA).

Content negotiation

agent-driven content negotiationnegotiate
In HTTP, the User-Agent string is often used for content negotiation, where the origin server selects suitable content or operating parameters for the response.
Content negotiation refers to mechanisms defined as a part of HTTP that make it possible to serve different versions of a document (or more generally, representations of a resource) at the same URI, so that user agents can specify which version fits their capabilities the best.

Session Initiation Protocol

SIPSession Initiation Protocol (SIP)SIP Trunking
The Session Initiation Protocol (SIP) protocol (based on HTTP) followed this usage.
In SIP, as in HTTP, the user agent may identify itself using a message header field (User-Agent), containing a text description of the software, hardware, or the product name.

Usage share of web browsers

usage sharebrowser market sharemarket share
A result of user agent spoofing may be that collected statistics of Web browser usage are inaccurate.
Measuring browser usage in the number of requests (page hits) made by each user agent can be misleading.

Safari (web browser)

SafariApple SafariSafari web browser
For example, the Android browser identifies itself as Safari (among other things) in order to aid compatibility.
The version number of Safari as reported in its user agent string is 3.0, in line with the contemporary desktop versions of Safari.

Cello (web browser)

Cello
Other browsers were considered to be older products such as Mosaic, Cello, or Samba, and would be sent a bare bones HTML document.
The user agent for Cello is.

Internet Explorer

IEMicrosoft Internet ExplorerExplorer
Web browsers created in the United States, such as Netscape Navigator and Internet Explorer, previously used the letters U, I, and N to specify the encryption strength in the user agent string.
Internet Explorer 11's user agent string now identifies the agent as "Trident" (the underlying layout engine) instead of "MSIE".

Netscape Navigator

NavigatorNetscapeMosaic Netscape
Web browsers created in the United States, such as Netscape Navigator and Internet Explorer, previously used the letters U, I, and N to specify the encryption strength in the user agent string.
The Mozilla name was also used as the User-Agent in HTTP requests by the browser.

Browser sniffing

detecting the browser being usedtarget or identify
Browser sniffing
Web pages can use programming languages such as JavaScript which are interpreted by the user agent, with results sent to the web server.

Web crawler

web crawlingcrawlercrawling
Web crawler
Web crawlers typically identify themselves to a Web server by using the User-agent field of an HTTP request.

Robots exclusion standard

robots.txtrobots exclusion protocola robot exclusion file
The User-Agent string is one of the criteria by which Web crawlers may be excluded from accessing certain parts of a website using the Robots Exclusion Standard (robots.txt file).
Many robots also pass a special user-agent to the web server when fetching content.

Mobile browser

mobile web browsermicrobrowserbrowser
Websites specifically targeted towards mobile phones, like NTT DoCoMo's I-Mode or Vodafone's Vodafone Live! portals, often rely heavily on user agent sniffing, since mobile browsers often differ greatly from each other.
Microsoft Bing — the option to enable or disable "Optimize web pages for your phone" in "Search settings" is not visible in Bing's mobile version as of March 2018. (The mobile version can be accessed with a phone or tablet, or when setting a web browser to identify itself with a mobile-based user agent string.)

WURFL

Wireless Universal Resource File (WURFL)WURFL, the Wireless Universal Resource File
Wireless Universal Resource File (WURFL)
User agent

Computing

computer technologycomputercomputational
In computing, a user agent is software (a software agent) that is acting on behalf of a user.

User (computing)

userusernameusers
In computing, a user agent is software (a software agent) that is acting on behalf of a user.

Web browser

browserweb browsersbrowsers
One common use of the term refers to a web browser that "retrieves, renders and facilitates end user interaction with Web content".

Email client

e-mail clientmail user agente-mail
For example, an email reader is a mail user agent.

Client (computing)

clientclientsclient software
In many cases, a user agent acts as a client in a network protocol used in communications within a client–server distributed computing system.

Communication protocol

protocolprotocolscommunications protocol
In many cases, a user agent acts as a client in a network protocol used in communications within a client–server distributed computing system.

Client–server model

client–serverclient-serverclient/server
In many cases, a user agent acts as a client in a network protocol used in communications within a client–server distributed computing system.

Operating system

operating systemsOScomputer operating system
When a software agent operates in a network protocol, it often identifies itself, its application type, operating system, software vendor, or software revision, by submitting a characteristic identification string to its operating peer.

String (computer science)

stringstringscharacter string
When a software agent operates in a network protocol, it often identifies itself, its application type, operating system, software vendor, or software revision, by submitting a characteristic identification string to its operating peer.

Internet bot

botbotsinternet bots
Bots, such as Web crawlers, often also include a URL and/or e-mail address so that the Webmaster can contact the operator of the bot.

URL

URLsweb addressuniform resource locator
Bots, such as Web crawlers, often also include a URL and/or e-mail address so that the Webmaster can contact the operator of the bot.