A rotary encoder is a device that converts the rotational position or motion of a shaft into an electrical signal. It is commonly used in various applications, such as robotics, industrial machinery, and consumer electronics, to provide precise control and feedback about the position of a rotating object. There are two main types of rotary encoders: incremental and absolute. Incremental encoders track movement by counting pulses as the shaft rotates, while absolute encoders provide a unique position value for each angle of rotation. This makes them useful for applications requiring accurate positioning and movement tracking.