A crossbow is a type of ranged weapon based on the bow and consisting of a horizontal bow-like assembly mounted on a frame which is handheld in a similar fashion to the stock of a gun. It shoots arrow-like projectiles called bolts or quarrels. The medieval crossbow was called by many names, most of which were derived from the word ballista, a torsion siege engine resembling a crossbow.
Historically, crossbows played a significant role in the warfare of East Asia and Medieval Europe. The earliest crossbows in the world were invented in ancient China and caused a major shift in the role of projectile weaponry. The traditional bow and arrow had long been a specialized weapon that required considerable user training, physical strength and expertise to operate with any degree of practical efficiency. In many cultures, bowmen were considered a separate and superior caste, despite usually being drawn from the common class, as their archery skill-set was essentially developed from birth (similar to many horseman cultures) and was impossible to reproduce outside a pre-established cultural tradition, which many nations lacked. In contrast, the crossbow was the first projectile weapon to be simple, cheap and physically undemanding enough to be operated by large numbers of conscript soldiers, thus enabling virtually any nation to field a potent force of ranged crossbowmen with little expense beyond the cost of the weapons themselves.
In modern times, crossbows have been largely supplanted by firearms in most roles, but are still widely used for shooting sports, hunting and when shooting with relative silence is important.