The Apache HTTP Server is cross-platform; as of 1 June 2017 92% of Apache HTTPS Server copies run on Linux distributions. Version 2.0 improved support for non-Unix operating systems such as Windows and OS/2. Old versions of Apache were ported to run on OpenVMS and NetWare.
Originally based on the NCSA HTTPd server, development of Apache began in early 1995 after work on the NCSA code stalled. Apache played a key role in the initial growth of the World Wide Web, quickly overtaking NCSA HTTPd as the dominant HTTP server, and has remained most popular since April 1996. In 2009, it became the first web server software to serve more than 100 million websites. As of July 2016, it was estimated to serve 46% of all active websites and 43% of the top million websites.
According to the FAQ in the Apache project website, the name Apache was chosen out of respect to the Native American tribe Apache and their superior skills in warfare and strategy. The name was widely believed to be a pun on 'A Patchy Server' (since it was a set of software patches). Official documentation used to give this explanation of the name, but in a 2000 interview, Brian Behlendorf, one of the creators of Apache, set the record straight:
The name literally came out of the blue. I wish I could say that it was something fantastic, but it was out of the blue. I put it on a page and then a few months later when this project started, I pointed people to this page and said: "Hey, what do you think of that idea?" ... Someone said they liked the name and that it was a really good pun. And I was like, "A pun? What do you mean?" He said, "Well, we're building a server out of a bunch of software patches, right? So it's a patchy Web server." I went, "Oh, all right." ... When I thought of the name, no. It just sort of connotated: "Take no prisoners. Be kind of aggressive and kick some ass."
When Apache is running, its process name is sometimes httpd, which is short for "HTTP daemon".