Accelerometers measure acceleration, vibration, and shock. An accelerometer involves the mounting of a seismic mass attached to a damper and a spring inside a solid casing.
The movement of the mass inside the casing is proportional to the force of acceleration on the device. Many accelerometers use either a capacitive or piezoelectric sensor to measure the position of the mass.
Accelerometers are specified by the range, frequency response, and the sensitivity of the device.