server

The date and time that the message was sent.

date

Control options for the current connection and list of hop-by-hop response fields.

The client or server would like to close the connection.

The time at which the response is considered stale.

Inform all caching mechanisms from server to client whether they may cache this object.

The time a browser should remember a site can only be accessed with https (seconds).

WordPress redirect agent.  A value of "WordPress" indicates that WordPress itself redirected the resource.

Indicates that different content may be provided to different clients, depending on the vary header.

This and all future requests should be directed to the given URI. The request method can change.

The last modified date for the requested object.

Standard response indicating a successful action. For GET requests this will be the resource, and for POST it will be the result of the action.