A SOCKET wrench, also known as a SOCKET driver, is a type of wrench or SPANNER that has a SOCKET attached at one end and is used to turn a fastener, such as a nut or bolt. It is usually hexagonal in shape and is commonly referred to as an ALLEN wrench. A LUG wrench is another kind of wrench that is used to loosen and tighten LUG nuts on vehicle wheels. All of these types of wrenches are used to tighten and loosen various types of fasteners.