An accelerometer is a device that measures acceleration forces, either static like gravity or dynamic caused by movement. It works by measuring the displacement of a spring-loaded mass. Accelerometers are used in many applications including tilt sensing, movement detection, freefall detection, car crash detection, medical devices, navigation, and more. There are 2-axis and 3-axis accelerometers, with the 2-axis Memsic 2125 measuring acceleration on two axes and the 3-axis MMA7260 measuring on three axes with selectable sensitivity ranges. An accelerometer's output can be read to detect changes in acceleration on each axis.