LG Tritan UX840 Quick Start Manual page 9

Accelerometer
Horizontal or vertical display? Your LG Tritan includes the new accelerometer
feature, which rotates the display from landscape to portrait to suit your needs!
To adjust the user interface, simply rotate the phone. The vertical view is ideal
for traditional phone use while the horizontal view is optimized for messaging
and web browsing with the QWERTY keyboard.
Enjoy music, photos, and messaging
in any direction with LG Tritan!