The Apache HTTP server is an open source HTTP web server, for Unix platforms, Microsoft Windows, Macintosh and others, which implements the HTTP / 1.1 protocol and the notion of a virtual site. When its development began in 1995 it was initially based on code from the popular NCSA HTTPd 1.3, but was later completely rewritten. Its name is because someone wanted it to have the connotation of something that is firm and energetic but not aggressive, and the Apache tribe was the last to surrender to what would soon become the US government, and at that time the concern of its group was that the companies arrived and "civilized" the landscape that the first Internet engineers had created. In addition Apache consisted only of a set of patches to apply to the NCSA server. And, a patchy server (a "patched" server) sounds the same as Apache Server.
The Apache server is developed and maintained by a community of users under the supervision of the Apache Software Foundation within the HTTP Server project (httpd).
Apache presents among other highly configurable features, authentication databases and content negotiation, but was criticized for the lack of a graphical interface that helps in its configuration.
Apache has wide acceptance in the network: since 1996, Apache, is the most used HTTP server. He played a fundamental role in the fundamental development of the World Wide Web and reached its maximum market share in 2005 being the server used in 70% of the websites in the world, however it has suffered a decrease in its market share in the last years. In 2009 it became the first web server that hosted more than 100 million websites.