Editing User-Agent header (section)

{{short description|Software acting on behalf of a user}}

{{pp-pc1}}
In [[computing]], the '''User-Agent header''' is an [[HTTP]] header intended to identify the [[user agent]] responsible for making a given HTTP request.  Whereas the character sequence <code>User-Agent</code> comprises the name of the header itself, the header value that a given user agent uses to identify itself is colloquially known as its '''user agent string'''. The user agent for the operator of a computer used to access the Web has encoded within the rules that govern its behavior the knowledge of how to negotiate its half of a request-response transaction; the user agent thus plays the role of the [[client (computing)|client]] in a [[client–server model|client–server system]].  Often considered useful in networks is the ability to identify and distinguish the software facilitating a network session.  For this reason, the User-Agent HTTP header exists to identify the client software to the responding server.