2.2.3.2.3 Set-Cookie Header Field
The Set-Cookie header field contains an opaque value of the form <cookie name>=<opaque string>. For details on the use of this header field, see section 3.2.5.1. Any Set-Cookie header value sent by the server to the client in response to a request is saved by the client for future use, as specified in section 3.1.1.