The Apache HTTP Server designed and developed to create a robust, commercial-grade, featureful, and freely-available source code
implementation of an HTTP (Web) server
Apache is a freely available Web server that is distributed
under an “open source” license Developed and maintained by Apache Software Foundation.
Version 2.0 runs on most
Unix-based operating systems (such as Linux, Solaris,
Digital UNIX, and AIX), on other UNIX/POSIX-derived systems
(such as Rhapsody, BeOS, and BS2000/OSD), on AmigaOS, and on
Windows 2000. 67% of the web servers are runninhg in apache in the world.
It is customizable to meet the needs of different environments by using extensions and modules.
The Apache binary running under UNIX is called HTTPd (short for HTTP daemon), and under win32 is called Apache.exe.
Apache’s main role is to communication over networks, and it uses the TCP/IP protocol .TCP/IP (Transmission Control Protocol/Internet Protocol) allows devices having IP address to communicate with one another within the same network.
The Apache server run on configuration files. In configuration file directives are added to control Apache behavior.
In its idle state, Apache listens to the IP addresses identified in its config file (HTTPd.conf).
Whenever it receives a request, it analyzes the headers, applies the rules specified for it in the Config file, and takes action.