A catapult is a weapon used to throw or hurl missiles without the aid of explosives, but the name is especially associated with siege engines. Various sorts of catapults used different kinds of ammunition, from bolts and arrows to wall-crushing boulders. The eairly katapaltai (meaning shield piercers in Greek) were basically arrow-shooting machines, and used against infantry. However, it was only in the Medieval Ages when catapults were mainly used in siege warfare, hurling stones for crushing, incendiary missiles for burning, and even corpses as an early form of biological warfare.