The Back , Start , and Search buttons get you around on your Windows phone and do a whole lot more. On phones that don’t have hardware buttons for navigation, the navigation bar puts these buttons right on your screen.
On phones without built-in buttons, reveal the navigation bar by putting a finger below the screen and swiping up.
Select the Back button to go back one screen from where you are. Your phone will take you back one page each time you press Back , until you get to the Start screen.
Press and hold the Back button to open the App switcher, and view all the apps you currently have open on your phone. Select any app to view it. You can leave more apps than ever open on your phone without affecting your battery life—navigating away will just pause the app where you left off.
Any time you select the Start button, you go back to the Start screen, no matter where you are on your phone or what you're doing.
Press and hold the Start button, and the screen will slide down so you can reach items at the top with one hand. To slide the screen back up, select the black space at the top of the screen.
Select the Search button and start typing to find answers on the web, or anything on your phone. Press and hold the Search button to dictate a question to your phone.