A crater is a circular depression or hole on the surface of a planetary body such as a planet, moon, or asteroid. It is typically bowl-shaped and can form in several ways: most commonly by the impact of a meteorite or asteroid, by volcanic activity, or by explosions near or below the surface. Impact craters are created when a smaller body hits the surface at very high speeds, producing shockwaves that displace material and leave a circular hole. Volcanic craters form around a volcano's vent where gases and magma erupt. Explosion craters result from blasts that eject ground material, creating a depression.

Thus, a crater is a landform with a hole or depression that can be caused by extraterrestrial impacts, volcanic eruptions, or explosive events.