The Apache HTTP Server is widely used to provide web sites and files to visitors on the Internet. It handles user requests, retrieves the page content from disk (or dynamically via an extension such as Apache Tomcat for JSP) and returns HTML code for display in the user's browser. Therefore, it performs a vital process that is required to serve web pages. The Apache source code is provided under an open source license. Other commercial HTTP server exist; one notable HTTP Server is the IIS by Microsoft, used widely on Windows Servers.

• Hyper-Text Transfer Protocol (HTTP)