Firefox 4 will heat up the battle between the open Web and downloadable apps.

Why? Because the new browser will enable developers to build applications using HTML5 that are similar to downloadable applications currently used on a number of mobile devices. These Web apps will include fully interactive graphics and games.

Firefox 4, which has been downloaded over thirty five million times, boasts a number of improvements:

• Increased privacy and security, including the "Do Not Track" feature for opting-out of third party advertisers.
   
• Interactive capabilities with HTML5 and without the need of external plug-in like Adobe Flash and Microsoft Silverlight
   
• Mozilla Sync feature to automatically sync bookmarks, open browser tabs and settings between computers, mobile phones and Android-based tablet computers (but not iPhone and iPad)

Mozilla did set up a Web site to showcase some advanced examples of the new browser's rendering engine. 

See also the Firefox Video Gallery.