A socket set, also known as a socket wrench, is a wrench with interchangeable heads known as sockets that attach to a fitting on the wrench and allow it to turn various sized bolts and other fasteners. The most common type is a hand tool known as a ratchet, which consists of a handle with a ratcheting mechanism built in, allowing it to be turned in tight spaces using a back-and-forth motion.
A socket is a cup-shaped fitting with a recess that holds a bolt’s head. The socket snaps onto the handle’s male fitting. The handle provides the mechanical advantage required to provide the torque required to turn the socket. The wrench is typically sold in a socket set that includes a variety of sockets to fit the heads of various sized bolts and other fasteners.
The benefit of a socket wrench is that it eliminates the need for a separate wrench for each of the numerous different bolt heads found in modern machinery, instead requiring only a separate socket. This saves space.