With stealthy automatic updates, you might not know that the Firefox 21 release date was today, but you may want to know about the its new features.

The official Firefox 21 release notes begin with the browser's integration of three additional social media networks.

"Today, we are adding multiple new social providers Cliqz, Mixi and msnNOW to Firefox," wrote Mozilla in a blog post today.

This is in addition to the inclusion of Facebook Messenger for Firefox, which has been baked into the browser ever since FireFox 17 released in November 2012.

According to Mozilla, these real-time updates will "help you stay connected to your social networks, no matter where you go on the Web."

What's new in Do Not Track, bug reports

The second pillar of what's new in FireFox 21 is an enhanced three-state user interface for Do Not Track.

The tweaked Do Not Track feature, located in the privacy tab, gives users the option to tell websites that they don't want to be tracked, do want to be tracked, or tell websites nothing at all.

More importantly, the third big change in today's Firefox download is the debut of Firefox Health Report.

The new feature should help users improve the browser's start-up time and reduce crashes thanks to tools that help them understand and actually fix problems.

Firefox users will no longer just encounter a somewhat useless "Report crash to Firefox" error screen, but have the chance to log and remedy the problem.

Firefox for Android update

Mozilla has kept its promise to simultaneously release Firefox for Android updates, launching a new version of the mobile browser in the Google Play store today.

The release notes for this pint-sized Firefox browser state that it adds access to recent history through the back and forward buttons and now includes the ability to save files via a long tap.

Mozilla also improved the fonts rendered by this browser in what it dubbed "Project Readability."

Mozilla's rapid release cycle estimates that the next Firefox browser update is due out toward the end of June.