An accelerometer is a device that measures acceleration, which is the rate of change of velocity. It detects changes in motion or orientation by sensing the forces acting on it. These sensors are commonly used in various applications, including smartphones, fitness trackers, and automotive systems, to provide data on movement and position. Accelerometers can be found in many everyday devices, such as smartphones that use them to rotate screens or track physical activity. In automobiles, they help with stability control and airbag deployment. Overall, accelerometers play a crucial role in enhancing user experience and safety in modern technology.