Mozilla Firefox is the second most used web browser in the world.
This beta version is distributed to the public in order to allow the users to identify and report possible flaws, that the developers will try to fix in the final version. In order to collect feedback from users, the program includes an add-on that allows them to report glitches to the developers.
The most visible change in this browser is the graphical interface. It becomes more attractive and easy to use. The program includes a feature called "Firefox Panorama", that opens a window in which you can open several web pages, group them by theme, zoom in or out, and choose how you want to display those slides, all in the same window.
Firefox also includes a "Sync" utility, that allows you to setup your browsing parameters through all the devices you use to connect to the Internet, through a server that keeps your data ready to be used by any of your devices.
Firefox 4 also has an improved method to manage the add-ons installed on it. Many add-ons and plug-ins for previous version of Firefox will not work in this version.