What are sockets used for?

Shop for Sockets

16mm Hex socket A socket is a tool that attaches to a socket wrench, ratchet, torque wrench or other turning tool in order to tighten or loosen a fastener such as a nut or bolt by turning it.

Common examples of where a socket is used

Spinner handle and socket being used on a car engine One of the most common places you see sockets being used is in automotive garages, where they can be used with turning tools such as ratchets, torque wrenches or impact wrenches. The socket and turning tool are used to tighten or loosen nuts and bolts on vehicles.
Impact wrench removing a car wheel. Impact sockets are often used with impact wrenches to remove wheel nuts from a car. The impact wrench applies a high torque (see Torque – Torque is the turning force of an object, and can be calculated by multiplying the force applied by the distance along the length of the lever used to apply it. Torque can be presented in either Newton metres (Nm) or pounds feet (lbft).) to the socket and wheel nut, helping to remove seized nuts.
Using a didgital torque wrench to assemble an engine Mechanics will often use a torque wrench with a socket to fit the cylinder head bolts to a cars engine. The torque wrench is used to provide a precise torque to the bolt, ensuring it is tightened sufficiently, whilst not over tightening it, which could damage the seal on the cylinder head.

See:  Which turning tools can be used with sockets? for more information on torque wrenches

Small sockets are used with a spinner handle for fixing the hard drives and side panels of desktop computers in place.
Socket bits such as in-hex sockets are used with ratchets to tighten or loosen Allen key type bolts often found on bicycles.

For more information on in-hex sockets see:  What is a socket bit?