Firefox 3.5 is based on the Gecko 1.9.1 rendering platform, which has been under development for the past year. Firefox 3.5 offers many changes over the previous version, supporting new web technologies, improving performance and ease of use.

What’s New In Firefox 3.5?

Some of the notable features are:

• Available in more than 70 languages.
• Support for the HTML5 <video> and <audio> elements including native support for Ogg Theora encoded video and Vorbis encoded audio.
• Improved tools for controlling your private data, including a Private Browsing Mode.
• Better web application performance using the new TraceMonkey JavaScript engine.
• The ability to share your location with websites using Location Aware Browsing.
• Support for native JSON, and web worker threads.
• Improvements to the Gecko layout engine, including speculative parsing for faster content rendering.
• Support for new web technologies such as: downloadable fonts, CSS media queries, new transformations and properties, JavaScript query selectors, HTML5 local storage and offline application storage <canvas> text, ICC profiles, and SVG transforms.

For more details, check out the Firefox 3.5 Release Notes.

Top 10 Firefox 3.5 Features
Check out Lifehacker’s post on Top 10 Firefox 3.5 Features. I have listed the points in below, for more details check out the site.

• Video superpowers with HTML 5
• Geo-location
• TraceMonkey JavaScript engine
• Color profiles that pop
• Private browsing mode
• Smarter session restore
• Keyword AwesomeBar filters
• Tab tearing
• Forget this site
• Undo closed window

Download: Get Firefox 3.5 now!