First impression of the crossbow

The crossbow is one of the most interesting weapons, as it had many advantages over its competitors and disadvantages. The crossbow is not as old as you think it is as its only over 2000 years old. The crossbow was discovered by the Chinese and since it was discovered many crossbow variations was invented. Such as

Acceleration system
Simple bow systems
Recurve bow systems
Springs with levers systems
Compound bow systems
Multiple bow systems

From the above variations of crossbow many different crossbow weapons where discovered. Such as the

Handheld crossbows with long stocks/gastraphetes
Pistol crossbows
Repeating crossbow and ballista
Multiple-bow arcuballista
Arbalest
Siege crossbows/oxybeles
Ballista
Bowguns