Instead, it informs the client that it can no longer use the existing HTTP connection to perform other HTTP requests on the same server, and that the client MUST close the connection as soon as it has finished handling the current request.
In any case, the web server will initiate a watchdog after script completion, and will force the deconnection after about 15 to 30 seconds if the client does not honor this header.
The exact time to wait for the "socket closed by remote" event is configurable in the web server. It is generally smaller when the "Connection: close" header has been sent by the server, than when no "Connection:close" has been sent in which case the connection persists for longer time, to let the client navigate on the server without enduring new connection costs in terms of: connection delays, number of socket control blocks in final wait state, number of used ports.
Don't doecon binäre option "Connection: close" on your server for every hosted page: this creates more incoming TCP connection attempts than necessary, and slows the navigation on your site.
Use it only if your script cannot generate explicit content length in the result header, as the client will have difficulties to determine the end of the results. See RFC for details.