Samsung GALAXY SIII User Manual page 27

Rotate
For most screens, you can automatically change the screen orientation from portrait to
landscape by turning the phone sideways. When entering text, you can turn the phone sideways
to bring up a bigger keyboard.
Note: The Auto rotate option must be enabled for the screen orientation to automatically
change. To make this selection, press > > Settings and tap My device > Display >
Auto rotate screen. See Auto rotate screen for more information.
Phone Basics 16