An accelerometer is a device that measures the proper acceleration of the device.
From Wikipedia:
An accelerometer is a device that measures proper acceleration. The proper acceleration measured by an accelerometer is not necessarily the coordinate acceleration (rate of change of velocity). Instead, 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.
For example, an accelerometer at rest on the surface of the earth will measure an acceleration of
g=9.81 m/s^2straight upwards, due to its weight. By contrast, accelerometers in free fall or at rest in outer space will measure zero. Another term for the type of acceleration that accelerometers can measure is g-force acceleration.
Most questions regarding this tag deal with how to access, interpret, and process accelerometer data that is abundant in smartphones.
