Mozilla Firefox 21 is readily available for download. This is a stable release channel update which includes specific improvements to Faster JavaScript, integrated PDF viewer fully written in Javascript and security updates. Stay Tuned and always download Mozilla Firefox latest release.

List of changes so done in this version are:
- NEW: The Social API now supports multiple providers
- NEW: Enhanced three-state UI for Do Not Track (DNT)
- NEW: Firefox will suggest how to improve your application startup time if needed
- NEW: Preliminary implementation of Firefox Health Report
- CHANGED: Ability to restore removed thumbnails on NEW: Tab Page
- CHANGED: CSS -moz-user-select:none selection CHANGED: to improve compatibility with -webkit-user-select:none
- CHANGED: Graphics related performance improvements
- CHANGED: Removed E4X support from Spidermonkey
- DEVELOPER: Implemented Remote Profiling
- DEVELOPER: Integrated add-on SDK loader and API libraries into Firefox
- HTML5: Added support for <main> element
- HTML5: Implemented scoped stylesheets
- FIXED: Some function keys may not work when pressed
- FIXED: Browsing and Download history clearing needs unification to avoid confusion on clearing download history
http://www.youtube.com/watch?v=YwOwJ1_JaKE&feature=player_embedded
There are lots more improvements in the it so the full list is not posted here. But as you’ll install and use the Firefox, you’ll come across the new features. Download links of Mozilla Firefox are:
Mozilla Firefox for Windows | All Systems and Languages
I did update to the new version and I have a weird thing
browser hangs – no response
restore open tabs, and it happens very often
probably soon will be a new release 18.1