Editor's note: This story was originally written for Firefox 3.5 Release Candidate 2, and has been updated for the final release of Firefox 3.5.
Mozilla today released Firefox 3.5, which you can download from Mozilla's Web site. Firefox 3.5 boasts a number of significant changes--ranging from new ways to work with the browser features to under-the-hood improvements that Mozilla developers say will make the browser more than twice as fast as Firefox 3. Here are some of the new features you'll find in Firefox 3.5.
Watch Nick explain the new features in Firefox 3.5.
Like a number of new browsers, Firefox 3.5 adds a private browsing mode to its arsenal of features. While in private browsing mode, Firefox won't remember anything--history, cookies, usernames, or passwords--from your session. When you start private browsing, Firefox closes all of the pages that you currently have open, but it saves all of your open windows so you can quickly get back to what you were doing before switching to private browsing, which is a nice touch.
Unlike the Incognito mode in Google Chrome (which shows a trenchcoat-and-hat-wearing silhouette icon in the toolbar) or the InPrivate Browsing mode of Internet Explorer 8 (which puts an 'InPrivate' bug in the address bar), Firefox 3.5 doesn't give any indication that you're in private browsing mode, aside from the initial on-screen message.
Firefox Gets Forgetful--On Purpose
To provide further privacy, Firefox 3.5 can "forget" any particular site. If I find myself checking my eBay auctions while at my desk (ahem), I can open the History panel, right-click any ebay.com reference, and choose 'Forget This Site'.
One important caveat: When you tell Firefox to forget a subdomain of a site, it won't forget other subdomains of that site. For example, if I tell Firefox to forget all history references for shop.ebay.com, it will cease to remember any Web address starting with 'shop.ebay.com', but not pages starting with 'cgi.ebay.com', so you may have to do a little digging to remove all references to a site from your history. Also, this feature seems to be disabled when private browsing is active; you can't "forget" sites from earlier normal browsing sessions while using private browsing.
Lost and Found
Firefox 3.5 now permits sites to find your location by using your IP address and by gathering data about nearby Wi-Fi networks, via Google Location Services (if you have WWAN card in your notebook, it will use cell-phone towers to find your location, just as Google Latitude does). This feature could be particularly useful for people who are visiting map sites or business user-review sites in search of nearby locations (though few sites support geolocation at present).
For the sake of your security and privacy, each site that wants to use your location must have your permission to do so. Firefox sends your IP address, nearby Wi-Fi networks, and a unique random ID (which expires after two weeks) to the server in order to find your whereabouts.
How accurate is the location finder? In casual experiments with Mozilla's geolocation test page (note: you can't try it out at all unless you're using Firefox 3.5), I used a Windows PC connected to our office's wired network and a Mac connected to the office's Wi-Fi network. The page found the Mac within a range of a couple blocks (not bad, all things considered), but it couldn't be any more specific for the Windows PC than the greater San Francisco Bay Area. This is likely because Firefox used nearby Wi-Fi hotspots, together with the Mac's IP address, to pinpoint its location; but for my wired PC, it had to rely solely on the PC's IP address. Still, if you're in a new city and are looking for nearby restaurants, Firefox's geolocation support could become quite useful when more sites incorporate it.
Tabs work better in Firefox 3.5 than in previous versions of the browser. Besides being able to rearrange the tab order, you can drag tabs off the toolbar and drop them either onto another Firefox window (to move the tab to that window), just as you could with Firefox 3.0. In Firefox 3.5, you can also drag a tab onto your desktop to create a new window containing that tab.
This feature is not unique to Firefox 3.5. Both Chrome and Safari include the same functionality, and aesthetically their implementations may be a bit smoother. For example, if you drag tabs around in Safari or Chrome, the tabs rearrange in real time, whereas in Firefox you'll get a marker indicating where the tab will go when you release the mouse button. In terms of functionality, though, Firefox's tear-off tabs work just as you'd expect them to.
Another subtle improvement to tabs is the addition of a small plus-sign (+) button on the tab bar, which makes creating a new tab a little more intuitive.
Get Back to What You Were Doing
Firefox 3.5 builds upon the previous Firefox's session-restore feature by remembering what you've entered into Web forms before you close the window. For example, suppose that I have to close the browser midway through replying to a reader comment on pcworld.com; when I reopen Firefox and restore my previous browser session, everything that I typed into the text box will still be there. It's about time a Web browser did this. A word of caution, though: If you start typing something that you don't want someone else to see later, be sure to delete it before you close the window.