Firefox is once again in the news for all the good reasons. It has come up with the drastically improved Firefox 3.5 in less than a year after the release of Firefox 3.0. Originally touted as Firefox 3.1, it was later renamed Firefox 3.5 to better reflect the amount of changes that happened in this new release. Though the official release has not yet happened, you can always try installing Firefox 3.5RC2 to get a first hand experience.

Here is a list of  features that i think is worth mentioning.

Introduction of HTML 5

Here is a Video introduction to HTML5 by the Mozilla team. Introduction of HTML 5 into the browser is arguably the highlight of the all new version of Firefox. HTML 5 will help you in further integrating video elements with the other contents in the website. And you dont need Flash or silverlight as plugins to run videos.

Open source video formats like Ogg and Theora have been integrated into browser and they form the heart of inbuilt video player for Firefox. This also means that, now you can insert links and other interactive elements to the video and also integrate it further to your blog to get a uniform and customised look and feel.

Tracemonkey JavaScript Engine

New Firefox 3.5 comes up with all new Trace Monkey javascript engine which got evolved from original Spider Monkey javascript engine, the one used in Firefox 3.0. According to official statistics from Mozilla, Trace Monkey Javascript engine is almost 20 times faster than its predecessor. Some other independent research also acknowledge this( though not as fast ). Trace Monkey is one of its  key improvement.

Private Browsing

Private browsing is a feature already in place in many of Firefox's competitors. Just consider the case in which you have to have to check your mail from your friend's laptop or sensitive research or simple bill paying, now all can be done securely using this private browsing feature. When private browsing is ON, Firefox wont store any records of the activities of the user.

Forget This SIte

Features like private browsing are all good to wipe out history from your browsers and you have your privacy intact. But Forget this site feature in new Firefox 3.5 takes the idea further. Now you can go to Histroy tab and clear individual sites from there. You wont loose the rest of it, not even the subdomains. That must be useful.

Improvised Tab Functionality

Again this is not a new feature, Google Chrome and Safari already have this tab tearing feature inbuilt. But nonetheless it is a useful one. You can simply drag a tab out to create a new browser window.

Undo Closed Window

This is yet another small but significant feature improvement. You already had undo closed tab funtionality (Ctrl + Shift + T) and now you can even undo a closed window. It is like icing on the cake. 

Enhanced Session Restore

Session restore was already there. What the mozilla team did was, they made it smarter. Now when a crashed session is restored, you can select which all tabs you want to restore. That is one cool hack.

Geo-Location

Firefox 3.5 brings in the "Where are you" factor where in firefox could be made to detect the location of the user.  It will help the websites to know your location without you entering the postal code yourself. In cases of you not knowing the postal code, this can be real helpful. As mozilla team puts it, you never know what all new functionalities are users going to find with geo location feature.

Before you cry foul over privacy issues, let me tell you, this is optional. You can disable it anytime. Take a look at Mozilla's official blog on geolocation in firefox 3.5. Now we know why IE is losing market share to Firefox.