::User agent


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{{#invoke:Protection banner|main}} In computing, a user agent is software (a software agent) that is acting on behalf of a user. For example, an email reader is a mail user agent, and in the Session Initiation Protocol (SIP), the term user agent refers to both end points of a communications session.<ref name="rfc3261">RFC 3261, SIP: Session Initiation Protocol, IETF, The Internet Society (2002)</ref>

In many cases, a user agent acts as a client in a network protocol used in communications within a client–server distributed computing system. 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. The SIP protocol (based on HTTP) followed this usage.

User agent sections
Intro  User agent identification  Use in HTTP  See also  References  

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