After 12 betas, two release candidates and more than nine months of development, Mozilla today officially released its next generation open source Firefox 4 Web browser.
With Firefox 4 -- the first major browser update since Mozilla released Firefox 3.6 in January of 2010 -- developers have made multiple user-facing changes that will noticed quickly by Firefox veterans. Tabs are now on top of the address bar by default, instead of below it as they have been since Firefox was first conceived. The user interface itself has been revamped in an effort to reduce clutter.
"We spent a bunch of time on the interface, making it as streamlined as possible, making it easy to get to the things that you want and also easy to get things out of your way," Johnathan Nightingale, director of Firefox at Mozilla, told InternetNews.com. "Moving from Firefox 3.6 to 4.0, we've compacted the interface, since most of the time users don't need the whole menu."
The "home" button has been moved to the right of the address bar and the RSS icon has also been removed from the default display. Nightingale stressed that Mozilla has not taken any functionality away from the browser. It has just moved items from the default display in an effort to improve usability and efficiency.
Firefox 4 also integrates the Firefox Sync technology, which enables users to synchronize their browser tabs and history across multiple systems. Firefox Sync extends to mobile platforms including Apple's iOS by way of the Firefox Home application.
Another key aspect of usability is the new Panorama feature, which enables users to group tabs together. Mozilla also looked to improve tabs with the addition of the a App Tab feature that pins a tab to the left of the browser.
"App Tabs is a recognition that the way people use the Web today is different," Nightingale said. "Something like Gmail is not simply a Web page that a user opens then closes, it's an application that happens to live on the Web."
Another tab improvement is delivered by way of a notification element. If something has changed within an App Tab in Firefox 4, a blue glow appears around the favicon. For example, if a user has a Gmail App Tab, whenever new email is received the tab will have a blue glow.
Mozilla's extension system has also undergone a dramatic change in Firefox 4. The new browser makes use of the new Mozilla Jetpack platform, which enables users to install and run extensions without the need to reload the browser.
Nightingale said that extensions that were not built with Jetpack will still also run in Firefox 4. Mozilla's add-ons site does identify which extensions require a restart and which ones do not.
On the security front, Firefox 4 includes Mozilla's Do Not Track implementation. With Do Not Track, browser users are able to alert sites whether or not they want to be tracked. However, it is still up to the Web sites themselves to actually add support for the specification. Both Google Chrome and Microsoft's IE 9 each has its own respective versions of a Do Not Track feature.
There is also a new Content Security Policy feature in Firefox 4 that could potentially mitigate most of the risk associated with Cross Site Scripting (XSS) attacks.
"Content Security Policy lets sites say where they expect to be loading content from," Nightingale said. "So if script is loaded from somewhere else, it's likely a XSS vulnerability on the Web site."
"The reporting aspect means that every Firefox 4 users makes the Web safer," Nightingale said. "If a Firefox 4 user is the first one to see an unauthorized script, we'll send back the ping and the site can see that and they can fix the bug."
The other key new security features is HTTP Strict Transport Security (HSTS), which can force SSL security to be used. The HSTS feature is important as it can help protect users against potential credential-sniffing attacks such as the one propagated by Firesheep earlier this year.
Having a fast browsing experience all begins with how fast the browser starts, which is also an area of improvement in Firefox 4.
"We're not interested in optimizing for a specific benchmark, but we're very interested in optimizing for common workloads," Nightingale said.