Mozilla Firefox is one of the World's most popular web browsers and was one of the first to break the stranglehold of Microsoft's Internet Explorer (IE) on the web browsing market.
With good reason too. Firefox remains an incredibly powerful and customizable browser although persistent memory leakage problems and competition from Google Chrome have dented its popularity.
There are a few interesting improvements in Firefox 21. There's a new Enhanced three-state UI for Do Not Track (DNT) to enhance privacy protection. Firefox should also start a bit quicker on your Mac as it suggests what can be done to improve start-up time (such as disabling certain unused add-ons). There's also a new Firefox Health Report feature which monitors how stable and well oiled your version of Firefox is. Other than this, there have been some minor cosmetic changes to functionality and some developer focused improvements.
The interface is pretty much the same as previous versions of Firefox, with a minimalist toolbar and there's still no way of removing elements that you may not want such as Java and .Net Framework. The major downside for most users however is that some plug-ins or add-ons won't work with the latest version of Firefox yet - so if you have a lot installed, prepare to be disappointed.
One major problem that persists is the high usage of RAM when Firefox is displaying Flash videos such as YouTube. Firefox runs an extra "Plugin-container" process for Flash videos that can occasionally consume 100% of your CPU and cause your Mac to freeze temporarily.
Something that's been introduced in more recent versions of Mozilla Firefox is Facebook integration. Firefox now supports Facebook's social API so you can have dedicated buttons for Facebook in your browser. Mozilla Firefox supports Facebook's Messenger within Firefox, giving users desktop notifications as well as a persistent friends list and activity feed on the right. Conversations will open up as overlays on top of whatever website you're on so you can multitask while you chat.
Mozilla Firefox 20 isn't a revolution in the development of Firefox, but there are some useful improvements that still make it a decent browser.
