Mozilla Firefox - faster, more secure, easier to use and sporting a new look, this latest Firefox release sets a new standard for web browser innovation. Mozilla Firefox project (formerly Firebird, which was formerly Phoenix) is a redesign of Mozilla's browser component, written using the XUL user interface language and designed to be cross-platform. It is small, fast and easy to use, and offers many advantages over other web browsers, such as the tabbed browsing and the ability to block pop-up windows. 
Mozilla Firefox 3 is focused on improved memory handling, performance, and stability, improved XUL, and new core components such as application data stored in SQLite. Mozilla Firefox 3 could break a few existing extensions and applications built on top of Firefox, and it will definitely include new optimizations if you like to build on the popular browser. Mozilla Firefox 3 should have additional JavaScript and SVG features if you're into that sort of thing.