RFC 2068:Hypertext Transfer Protocol -- HTTP/1.1
RFC-Ref

role


Click on the red underlined text to get to the source

... This specification uses a number of terms to refer to the roles played by participants in, and objects of, the HTTP communication. ...
... be capable of being both a client and a server; our use of these terms refers only to the role being performed by the program for a particular connection, rather than to the program's capabilities ...


... The first digit of the Status-Code defines the class of response. The last two digits do not have any categorization role. There are 5 values for the first digit: ...


... network address of the client), play a role in the selection of the response representation. Subsequent requests on that resource can only be properly interpreted by the origin server, and thus a cache ...



Google
Web
RFC-Ref