httpd, HyperText Transfer Protocol Daemon] is a generic, full featured server for serving files using the HTTP protocol. This is a TCP/IP based protocol running by convention on port 80.
Files can be real or synthesized, produced by scripts generating virtual documents. It handle clickable images, fill-out forms, and searches etc.
httpd can also be run as a proxy server to allow people behind firewalls
to use the Web as if the firewall was not present. A powerful
feature is caching performed by the
proxy, which makes
cern_httpd as proxy attract even
those not inside a firewall.