Hammer (tool)

A hammer is a tool that delivers a discrete impact to an object; the object can be another tool that is powered by the hammer blow, such as a chisel (tool); an object that is moved by the blow (e.g., a nail (fastener) or a beam being forced into place); or an object to be disrupted by force (e.g., concrete to be shattered). Muscle-powered hammers are among the earliest known tools, in the form of suitably shaped stones, but there is a wide range of specialized hand-operated hammers, as well as hammers driven by an external power source.

The basic principle of hammering — delivering successive impacts rather than a continuous motion — is present in variants of other tools, such as a hammer drill or impact wrench.

Hand-operated hammers come in a great variety of sizes, shapes, and materials both of the striking surface and the parts of the hammer that direct force to that surface.