Socket wrenches can be divided into three basic types based on the method of driving their sockets: Hand-held ratchets, pneumatic impact wrenches and hydraulic torque wrenches. The hand-held ratchets feature a reversible ratcheting mechanism that allows the user to pivot back and forth to turn their socket without having to remove and reposition a wrench.
Hex socket wrenches (also called 6-point sockets) are the most common type of fastener socket, and form six points of contact with a nut or bolt head to offer reliable purchase for tightening and loosening. They can be purchased in a wide range of drive sizes to suit a variety of applications, and many feature slightly convex internal socket faces that reduce the risk of stripping or rounding-out fasteners at their corners.
The most important step to ensuring a good fit is selecting the correct socket size. Choosing a socket too small can cause the fastener to get trapped, while one too large can trap it and require a lot of work to free it.