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.
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 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.
Read more about User Agent: User-agent Identification, User Agent Spoofing, User Agent Sniffing, Encryption Strength Notations
Famous quotes containing the words user and/or agent:
“A worker may be the hammer’s master, but the hammer still prevails. A tool knows exactly how it is meant to be handled, while the user of the tool can only have an approximate idea.”
—Milan Kundera (b. 1929)
“The average American is a good sport, plays by the rules. But this war is no game. And no secret agent is a hero or a good sport—that is, no living agent.”
—John Monks, Jr., U.S. screenwriter, Sy Bartlett, and Henry Hathaway. Robert Sharkey (James Cagney)