The open-source web server software commonly used on Linux is Apache, more precisely the Apache HTTP Server.
Apache began in 1995, when developers continued work on the NCSA HTTPd codebase after its original development slowed. It is maintained by the Apache Software Foundation and released under the Apache License 2.0. Although it runs on Windows and other Unix-like systems, Apache has historically been especially common on Linux servers.
Apache serves web pages and applications over HTTP and HTTPS. Its modular design lets administrators add features such as authentication, URL rewriting, proxying, and scripting support. Virtual hosting also allows one installation to serve multiple domain names.
Apache is sometimes confused with Nginx or LiteSpeed, which are separate web-server products. The name Apache refers to the server project; “Apache” alone is the common short form for Apache HTTP Server.