Gyroscope - Measures angular rotational velocity to detect rotation of the device.
Accelerometer - Measures the linear acceleration of movement to detect the orientation of the device.
Digital Compass - The digital compass or magnetometer provides simple orientation in relation to the Earth's magnetic field. As a result, the device always knows which way is North so it can auto-rotate digital maps, depending on the physical orientation of the device.
Light Sensor - Detects ambient light and adjusts the screen brightness.
