Mozilla today officially released Mozilla Firefox 4, the newest version of the popular and open source Web browser.

Firefox 4 provides a streamlined user interface, new features, a boost in speed and support for modern Web technologies.

Firefox 4 is available to download for Windows, Mac OS X and Linux in more than 80 languages. Firefox 4 will also be available on Android and Maemo devices soon.

Mozilla claims that the new Firefox 4 is the fastest Firefox yet, being between two and six times faster than previous releases. Enhancements to the JavaScript engine make everything from startup time to page load speed to graphics and JavaScript performance fast in Firefox.

The latest version of Firefox also introduces a sleek new look. With features like App Tabs and Panorama, Firefox makes it easier to navigate the Web. Privacy and security features like Do Not Track and Content Security Policy also give users control over their personal data and protect them online.

Firefox Sync gives users access to their Awesome Bar history, bookmarks, open tabs and passwords across computers and mobile devices. Firefox also offers many add-ons, extensions and Personas and a new Firefox Add-ons Manager to make it easy for users to manage and discover add-ons.

Firefox supports modern Web technologies, including HTML5.

What?s New in Firefox 4:

Performance: Firefox is up to six times faster than the previous release, offering improved start-up and page load times, speedy Web app performance and hardware accelerated graphics.

App Tabs: give a permanent home to frequently visited sites like Web mail, Twitter, Pandora, Flickr.

Switch to Tab: easily find and switch to any open tab from your Awesome Bar without opening duplicate tabs.

Panorama: drag and drop tabs into manageable groups to save time while navigating many open tabs.

Firefox Sync: access your Awesome Bar history, bookmarks, open tabs, passwords and form data across multiple computers and mobile devices.

New Add-ons Manager: easily discover and install add-ons to customize the features, functionality and look of Firefox.

Do Not Track: A universal standard Do Not Track feature that allows users to opt-out of tracking used for behavioral advertising.

Firefox fixes flaws in some Web standards to prevent others from accessing your browser history.

HTTP Strict Transport Security (HSTS): automatically establishes secure connections to stop "man in the middle" attacks and keep sensitive data safe from interception during the log-in process.

Content Security Policy (CSP): prevent cross-scripting attacks by allowing sites to explicitly tell the browser which content is legitimate.

Tools for Web Developers:

The JavaScript engine incorporates the new JagerMonkey JIT compiler, along with enhancements to the existing TraceMonkey JIT and SpiderMonkey?s interpreter for faster page-load speed and better performance of Web apps and games.

HTML5 support in Firefox includes hardware accelerated, high-definition video (WebM), 3D graphics, offline data storage, professional typography, touchscreen interfaces and the Mozilla Audio API to help create visual experiences for sound and more.

Firefox 4 also improves existing tools like CSS, Canvas and SVG to enable developers to make exciting Web pages.

Firefox provides uninterrupted browsing when there is a crash in the Adobe Flash, Apple QuickTime or Microsoft Silverlight plugins. If one of these plugins crashes or freezes, it won?t affect the rest of Firefox. Simply reload the page to restart the plugin.