A hammer is a tool or device that delivers a blow (a sudden impact) to an object. Most hammers are hand tools used to drive nails, fit parts, forge metal, and break apart objects. Hammers vary in shape, size, and structure, depending on their purposes.
Hammers are basic tools in many trades. The usual features are a head (most often made of steel) and a handle (also called a helve or haft). Although most hammers are hand tools, powered versions exist; they are known as powered hammers. Types of power hammer include steam hammers and trip hammers, often for heavier uses, such as forging.
Some specialized hammers have other names, such as sledgehammer, mallet, and gavel. The term "hammer" also applies to devices that deliver blows, such as the hammer of a firearm, or the hammer of a piano, or the hammer ice scraper....LESS