Apache HTTP Server

What is it?
The Apache HTTP Server is a powerful and flexible HTTP/1.1 compliant web server. Originally designed as a replacement for the NCSA HTTP Server, it has grown to be the most popular web server on the Internet. As a project of the Apache Software Foundation, the developers aim to collaboratively develop and maintain a robust, commercial-grade, standards-based server with freely available source code.

The Latest Version
Details of the latest version can be found on the Apache HTTP server project page under:
http://httpd.apache.org/

Documentation
The documentation available as of the date of this release is included in HTML format in the docs/manual/ directory. The most up-to-date documentation can be found at:
http://httpd.apache.org/docs-2.0/