Back, start, and search keys
The back, start, and search keys help you to navigate your phone.
Back key 
Return to the previous screen
Press . Your phone remembers all the apps and websites you have visited since the last time your screen was locked.
Switch between open apps
Press and hold , swipe left or right, and select the desired app.
Start key 
Go to the start screen
Press .
Control your phone with your voice
Press and hold , and say a voice command.
This feature may not be available in all languages.
Search key 
Search the web
Press .