Mozilla Firefox is a free and open source^[10] web browser developed for Microsoft Windows, OS X and Linux (including Android) coordinated by Mozilla Corporation and Mozilla Foundation. Firefox uses the Gecko layout engine to render web pages, which implements current and anticipated web standards.^[11]
As of October 2012, Firefox has approximately 20% to 24% of worldwide usage share of web browsers, making it the second or third most widely used web browser, according to different sources.^{[12][13][14][15]} According to Mozilla, Firefox counts with over 450 million users around the world.^[16] The browser has had particular success in Indonesia, Germany, Poland and Estonia, where it is the most popular browser with 65%,^[17] 47%^[18] 47%^[19] and 35%^[20] of the market share, respectively.(http://en.wikipedia.org/wiki/Firefox)