We typically think of a catapult as something that was used in the Middle Ages to destroy the walls of a castle as in the poster shown here. But Catapults have a very long history dating long before the time of castles and they were developed and designed in many different ways by many different cultures over the centuries.
What is a catapult? The general definition is that a catapult is a machine that stores energy then quickly releases the energy to fire a projectile. To be a catapult the machine generally has to be too large for a person to carry. If we just used the storage and release of energy to define a catapult then a longbow would also fit this definition. So the size of the machine is important.