A hammer is a tool meant to deliver an impact 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. 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.

History

The use of simple tools dates to about 2,400,000 BCE when various shaped stones were used to strike wood, bone, or other stones to and break them apart and shape them. Stones attached to sticks with strips of leather or animal sinew were being used as hammers by about 30,000 BCE during the middle of the Paleolithic Stone Age. Its archeological record means it is perhaps the oldest human tool known.

Designs and variations

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

The opposite side of 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.
• Splitting 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

image:hammer2.jpg|Claw hammer Image:Framing hammer.jpg|Framing hammer Image:BrokenConcretion22.jpg|Geologist's hammer Image:Hammer tapissier.jpg|Upholstery hammer Image:Hammer-1.jpg|Cross-peen hammer Image:Ball-peen hammer 380mm.JPG|Ball-peen hammer Image:Mallet.jpg|Rubber mallet Image:Wooden mallet.jpg|Wooden mallet Image:Sledgehammer.jpg|Sledgehammer image:Hammer stone tapping.jpg|Stone tapping hammer Image:Hammer stone head.jpg|Perforated hammer head of stone Image:Hammer Long cross-face.jpg|Long cross-face hammer (blacksmithing) Image:Hammer twist.jpg|Twist hammer (blacksmithing) Image:Hammer dog-head.jpg|Dog-head hammer (blacksmithing) Image:Hammer ball pane.jpg|Ball pane hammer Image:Hammer straight pane sledge.jpg|Straight pane sledgehammer