- Firefox redirects here. For the novel and film of this title, see Firefox (novel and film). For other uses, see Firefox (disambiguation).
Mozilla Firefox is a free, open source web browser developed by the Mozilla Foundation. The software is licensed under the Mozilla Public License version 1.1 and is the main competitor of Microsoft's Internet Explorer. The current stable release is version 11.0.
Firefox was originally developed as an offshoot of the Mozilla Browser project, developed by Netscape, as a lightweight version of the software. The original Mozilla browser was extremely feature rich, including such things as an HTML editor, which created a large and correspondingly slow piece of software. Firefox has gone through several name changes, all due to existing trademarks. It was originally named Phoenix, then Firebird and finally Firefox.
Since its original release in 2002, Firefox has had a continued increase in the market share of web browsers until 2009, then a small decline due to competition from Google Chrome. Exact numbers are difficult to determine, but as of May 2011 worldwide, Firefox had a 22% share, and as of March 2011, 29.5% in Europe.
The browser is officially supported in over 70 languages, and is available for the different versions of Microsoft Windows, Apple Mac OS X, and Linux operating systems. Unofficial builds are available for Sun Microsystems Solaris, BSD, and other operating systems.