While Mozilla still pinpoints more than 3,000 bugs for the browser, few of them threaten the average user anymore.

Some of the flaws patched — like modified image files from the Cairo graphics library, or Mesa graphics drivers causing WebGL to crash on Linux systems — were quite dangerous, but fairly obscure. Others — such as shared permissions between tabs, issues with updater authorization and memory corruption while loading grayscale images — were potentially much more troublesome.

In terms of what will actually be useful to the end user, Firefox 20's new tab functionality is probably the most salient. Previously, users wanting to browse the Web privately would have to start up a new session of Firefox. Now, users can set the privacy of each individual tab, saving them the trouble of having to run multiple Firefox windows or restart the browser.

Users with many plug-ins installed are also intimately familiar with the annoyance that comes with one of them crashing. If a single plug-in ceases to function, the entire browser used to hang in suspended animation as Firefox attempted to address the issue. In the new version, unless the plug-in directly affects the content on a Web page, a malfunctioning plug-in will not cause the whole browser to freeze up.

The download manager also experienced a small redesign. Instead of taking users to a separate download page, a small clickable arrow shows their pending downloads unobtrusively.

Updating is simple and shouldn't take long. Click on Firefox's main menu, followed by "Help" and "About Firefox. It will begin hunting for the update data immediately. If you're a few versions behind, just go through the same sequence each time the program restarts, and you'll hit Version 20 within a few iterations.

The security fixes are all well and good, but the ability to assign privacy settings to tabs on the fly is quite exciting, especially if you share your computer with other people. Other browsers would do well to adopt the same paradigm.