Compass (iPhone Only)

The iPhone 3GS, iPhone 4, and iPhone 4S have a built-in magnetometer—a bit of circuitry that measures the direction of the Earth’s magnetic field. Launch this app, and the iPhone is likely to tell you the direction it’s pointing in by using a traditional compass face.

At the bottom of the screen are the geographic coordinates (degrees, minutes, and seconds indicating where the iPhone believes that it is). Tap these coordinates, and the iPhone may display an address to accompany your location. To the left of these coordinates is the Location icon. Tap it, and Maps opens, showing you your location as determined by the iPhone. In the bottom-right corner of the Compass screen is the Info button. Tap it, and you can choose whether the iPhone points to true north or magnetic north.