Mozilla promised a new version of Firefox three months post Firefox 4’s release and rolled out a whole rapid release development cycle to ensure they met the deadline and true to their word Firefox 5 is now available for download. As per Mozilla, the new version has some 1000 changes though the more notable ones are better support for HTML 5, faster start-up and the Do Not Track feature that lets you stop sites from tracking your web history.
To enable the Do Not Track feature, access the Options window from the Tools menu. A new option has been added in the Privacy tab under Tracking. Check Tell web sites I do not want to be tracked to enable the feature.
Apart from that, the browser now offers better support for HTML 5 and for CSS animation standards. It also looks like the era of no restart add-ons is dawning for Firefox; according to the official blog posting, it should now be easier for developers to build no restart add-ons for all platforms.
Mozilla has also simultaneously released Firefox 5 for Android, read more about it here.