A crowbar is a hand tool made of a metal bar, usually medium-carbon steel, with a single curved end and flattened points. It works as a lever: you use it to force two objects apart, pry up boards, or gain mechanical advantage when lifting something heavy. The curved end often has a notch (a split claw) for pulling nails.
The curved end usually acts as a first-class lever, with the bend serving as the fulcrum, while the flat chisel end is used as a second-class lever. Crowbars are also called wrecking bars, pry bars, or pinch bars, and flat versions are often called utility bars. The name is generally traced to the bird, possibly because the forked end resembles a crow’s foot or beak, and the term dates back to about 1400.
Source: Wikipedia: Crowbar
Image: Standard crowbar, public domain, via Wikimedia Commons.