A hand tool is a device for doing a particular job that does not use a motor, but is powered solely by the person using it.

Examples are almost endless, from general tools like the hammer to specific tools like callipers. Some hand tools are mounted to walls, such as pencil sharpeners.

Virtually every type of tool can be a hand tool, although many have also been adapted as power tools, which get their motive power from engines rather than from people. Some hand tools cannot be easily or safely converted to power tools, for example chisels. Other examples are used by laborers such as hammer and saw.

A hammer is a tool meant to deliver blows to an object. The most common uses are for driving nails, fitting parts, and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure. Usual features are a handle and a head, with most of the weight in the head. The basic design is hand-operated, but there are also many mechanically operated models for heavier uses.

The hammer is a basic tool of many professions, and can also be used as a weapon. Either way, it is perhaps the oldest human tool, perhaps even older than the earliest Homo species

By analogy, the name hammer has also been used for devices that are designed to deliver blows, e.g. in the caplock mechanism of firearms.

The essential part of a hammer is the head, a compact solid mass that is able to deliver the blows to the intended target without itself deforming.

The opposite side of the head may have a second striking surface; or a claw or wedge to pull nails, or may be shaped like a ball as in the ball-peen hammer and the cow hammer. Some upholstery hammers have a magnetized appendage, to pick up tacks. In the hatchet the hammer head is secondary to the cutting edge of the tool.

In recent years the handles have been made of durable plastic or rubber. The hammer varies at the top, some are larger than others giving a larger surface area to hit different sized nails and such,

Popular hand-powered variations include:

• carpenter's hammers (used for nailing), such as the framing hammer and the claw hammer
• upholstery hammer
• construction hammers, including the sledgehammer
• drilling hammer - a lightweight, short handled sledgehammer
• ball-peen hammer, or mechanic's hammer
• cross-peen hammer, or Warrington hammer
• mallets, including the rubber hammer and dead blow hammer.
• maul
• stonemason's hammer
• Geologist's hammer or rock pick
• lump hammer, or club hammer
• gavel, used by judges and presiding authorities in general
• Tinner's Hammer

Claw hammer	Framing hammer	Geologist's hammer	Upholstery hammer
Cross-peen hammer	Ball-peen hammer	Rubber mallet	Wooden mallet
Sledgehammer

Mechanically-powered hammers often look quite different from the hand tools, but nevertheless most of them work on the same principle. They include:

• jackhammer
• steam hammer
• trip hammer
• hammer drill, that combines a jackhammer-like mechanism with a drill

In professional framing carpentry, the hammer has almost been completely replaced by the nail gun. In professional upholstery, its chief competitor is the staple gun.