There are two commonly used servers, from NCSA and CERN. They
both offer similar features, although there are important differences.
This list points to relevant introductory documents for these servers
(and some others that are important) and points out some of the
differences and features. For additions and suggestions to this
list mail email@example.com (please refer
to the document you are commenting on).
The NCSA httpd-1.1 is an http/1.0 compatible
server. Its most important feature is the ability to allow
server-side includes (i.e. files or script
output can be embedded within a document, on the fly).