The 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. 

Firefox is a small, fast and very easy to use browser that offers many advantages over other web browsers, such as the ability to block pop-up windows and the tabbed browsing. 

Features: 

Comprehensive popup controls to keep unwanted advertising off your desktop; 

A tab browsing mode that lets you open several pages in a single window, allowing you to load links in the background without leaving the page you're on; 

Integrated search (powered by Google); 

Industry leading accessibility with Find As You Type - find links and page text by simply typing; 

Simplified privacy controls that let you cover your tracks more effectively; 

A streamlined browser window that lets you see more of the page than any other browser while at the same time being more configurable; 

A large variety of free downloadable extensions and themes that add specific functionality and visual changes to the browser.