Apache is the most popular web server software. It was originally designed for Unix systems but has been ported to other operating systems like Windows. Apache uses configuration files to manage settings. The main configuration file is httpd.conf which contains general settings, while other files like access.conf and srm.conf are now typically empty as settings are placed directly in httpd.conf.

1. : Apache is generally recognized as the world's most popular Web server (HTTP server).Originally designed for Unix servers, the Apache Web server has been ported to Windows and other network operating systems (NOS) .

2. The name "Apache" derives from the word "patchy" that the Apache developers used to describe early versions of their software.

3. Apache also supports plug-in modules for extensibility.

4. Apache is reliable, free, and relatively easy to configure.

5. Apache is free software distributed by the Apache Software Foundation.

6. The Apache Software Foundation promotes various free and open source advanced Web technologies.

7. HTTP

8. IIS

9. SSL Apache Web Server

10. HTTP Definition: HTTP - the Hypertext Transfer Protocol - provides a standard for Web browsers and servers to communicate.

11. The definition of HTTP is a technical specification of a network protocol that software must implement.