An accelerometer is a device that measures proper acceleration. The accelerometer sees the acceleration associated with the phenomenon of weight experienced by any test mass at rest in the frame of reference of the accelerometer device. Another term for the type of acceleration that accelerometers can measure is g-force acceleration. Accelerometers have multiple applications in industry and science. Highly sensitive accelerometers are components of inertial navigation systems for aircraft and missiles. Accelerometers are used to detect and monitor vibration in rotating machinery and can also be used in tablet computers and digital cameras so that images on screens are always displayed upright.