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.
Proximity Sensor - Detects the presence of nearby objects without physical contact. The sensor detects when the device close to your face during a call and turns off the screen, preventing unintentional screen touches.