UserAgent is a String property that contains information about the user agent originating the HTTP request. 

UserAgent is the the client which initiates a request. These are often browsers, editors, spiders (web-traversing robots), or other end user tools. UserAgent is used 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. 

UserAgent can contain multiple product identifiers and comments identifying the agent and any subproducts which form a significant part of the user agent. For example: 

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

UserAgent should be provided for all HTTP requests. 

UserAgent will be reset to its default value in the Clear method.