A snap ring is a type of fastener used to secure components within a mechanical assembly. It is typically made of metal and has a circular shape with a gap that allows it to be easily installed or removed. Snap rings are commonly found in machinery, automotive applications, and various devices to hold parts in place, preventing them from sliding out of position. There are two main types of snap rings: internal and external. Internal snap rings fit into a groove inside a bore, while external snap rings fit into a groove on the outside of a shaft. Both types provide a reliable method for retaining components, ensuring the proper functioning of devices like motors, gearboxes, and pulleys.