MEMS accelerometers are used wherever there is a need to measure linear motion, either movement, shock or vibration but without a fixed reference.  They measure the linear acceleration of whatever they are attached to. Acceleration is measured in m/s-2, but the convention for accelerometers is in ‘g’, or units of gravity, 1g being 9.81m/s-2.

All accelerometers work on the principle of a mass on a spring, when the thing they are attached to accelerates then the mass wants to remain stationary due to its inertia and therefore the spring is stretched or compressed, creating a force which is detected and corresponds to the applied acceleration.