Textbook of Linux

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Apache HTTP Server

A widely deployed open-source web server.

The Apache HTTP Server is a modular web server developed under the Apache Software Foundation. It pioneered modules such as mod_rewrite for URL manipulation, mod_ssl for HTTPS, mod_php for PHP execution, and a huge ecosystem of third-party modules covering authentication, caching, compression, and almost every other web concern. The .htaccess mechanism — per-directory configuration overrides — has been particularly important for shared hosting.

Apache was the most popular web server on the public internet for over two decades, serving more than 60% of all websites at its peak in the early 2000s. It has since traded the top spot with NGINX and Cloudflare's edge, but remains one of the three most-deployed web servers in the world. Many shared-hosting providers and many established corporate web servers run Apache.

The Apache Software Foundation has been the project's home since 1999. The foundation's broader governance model and "Apache Way" of decision-making originated with this server project. The Apache 2.0 licence — among the most-used permissive free-software licences in existence — also originated here. The codebase is mature and conservative, with releases every few years bringing incremental improvements and security fixes.

Debian/Ubuntu: sudo apt install apache2
Fedora/RHEL:   sudo dnf install httpd
Arch:          sudo pacman -S apache
macOS:         brew install httpd