The OS completely tosses out any permanent buttons, be they Home, Back, or anything else, in favor of a gesture-based system. You trigger different functions by swiping in from the sides or top of the screen, a bit like on Windows 8 (or on WebOS, if you go back a few years). Swipe in from the left and you'll get a sort of dock showing your most frequently used apps, while swiping in from the right cycles through recently used apps to function as an app switcher. Swipe down from the top to access messages and change settings. That last seems like a great idea, a bit like Android's notification shade but with even more options, since you can move left and right to access other menus. (Swipe down on the messages icon to see messages, but then move right to see connection options, move further right to see screen options, that kind of thing.) Swiping up from the bottom within an app gives you more options, like the Menu button in Android.