User-agent is typically, but not always, a WEB Browser.

User-agent is (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.

User-agent request-header[2]#

The User-agent request-header field contains information about the User-agent originating the request. This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations. User agents SHOULD include this field with requests. The field can contain multiple product tokens and comments identifying the agent and any subproducts which form a significant part of the user agent. By convention, the product tokens are listed in order of their significance for identifying the application.
User-Agent     = "User-Agent" ":" 1*( product | comment )


User-Agent: CERN-LineMode/2.15 libwww/2.17b3

More Information#

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