Mozilla Firefox is a web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. Official versions are distributed under the terms of a proprietary EULA. Firefox had 22.05% of the recorded usage share of web browsers as of March 2009, making it the second-most popular browser in current use worldwide, after Internet Explorer.
To display web pages, Firefox uses the Gecko layout engine, which implements some current web standards plus a few features which are intended to anticipate likely additions to the standards.
Firefox runs on various versions of Microsoft Windows, Mac OS X, Linux, and many other Unix-like operating systems. Its current stable release is version 3.0.8, released on March 27, 2009. Firefox’s source code is free software, released under a tri-license GNU GPL/GNU LGPL/MPL.