HTTP/1.1 Connection header field
The Connection general-header field allows the sender to specify options that are desired for that particular connection.
It is defined in RFC 2616, section 14.10.
If an option has parameters associated with it, they can be included in a specific header field with the same name as the option, e.g. see Keep-Alive.
This header must not be communicated by proxies over further connections; proxies must also remove any additional header fields whose names match those of options specified in the Connection field.
HTTP/1.1 defines the "close" connection option for the sender to signal that the connection will be closed after completion of the response, e.g. the connection should not be considered persistent.
HTTP/1.1 applications that do not support persistent connections must include the "close" connection option in every message.