Firefox 1.0 was released 10 years ago yesterday, and as a celebration of sorts, Mozilla released a new version of the browser that's intended to help users control their privacy online as well as a new developer-oriented version of the browser.

The main feature of the new Firefox release, 33.1, is a "Forget" button on the toolbar that can instantly wipe the last five minutes, two hours, or one day of browsing history, cookies, and tabs. This isn't a new capability itself—the Privacy panel of the options dialog has long offered this ability—but in Firefox 33.1, it's now instantly accessible.

The new release also adds DuckDuckGo as a search engine. DuckDuckGo positions itself as a more private search engine, one that tracks less user data while recording no search history and having no identifiable user accounts.

On top of all that, Mozilla launched the Polaris Privacy Initiative, an effort to develop technology to enhance browser privacy. Two Polaris experiments were announced today. First, Mozilla is working more closely with the Tor Project. The Tor Project uses Firefox as the browser in its Tor Browser Bundle, and the Tor engineers have suggested a list of changes to Firefox that would make using Firefox and Tor together better. Mozilla is investigating whether these changes can be incorporated into Firefox. The browser developer is also going to host Tor servers of its own, increasing the capacity of the anonymous network.

Second, Mozilla is taking another stab at preventing advertisers from tracking user activity across the Web. This will use blacklists that prevent access entirely to certain domains used by third-party trackers. This feature is currently being tested and developed in Firefox's Nightly builds.

Firefox Developer Edition is a new variant of Firefox that replaces the Aurora channel running two versions ahead of the stable release (so currently, Firefox stable is version 33, Beta is 34, and Aurora/Developer is 35). It's designed to both give developers an early look at forthcoming features and to be a better platform for Web development in general.

Firefox already includes extensive developer features, including a development environment. Firefox Developer Edition makes these things easier to use by, for example, including Mozilla's add-in that lets Firefox debug Web content on iOS and Android. It also comes pre-configured to support remote debugging.

The new offering even has a fancy dark theme that makes it look visually distinct from the regular Firefox edition.