Mozilla has released a preview version of a completely revamped Firefox browser app for Android. Firefox Preview uses Mozilla's own GeckoView web rendering engine instead of Google's Blink. This enables Tracking Protection by default, which keeps advertisers and bad actors from tracking your activity across different web sites. Mozilla also promises speeds up to twice as fast. GeckoView and Tracking Protection debuted in the minimalist Focus browser app. Mozilla is now folding these features into its more full-featured Firefox browser. Firefox Preview also includes Collections, which lets users define a set of web sites to open at once, such as "morning routine" or "travel planning". Firefox Preview is available now, and with the final version available as the Firefox app this fall.