A 
ball is a round object that is used most often in 
sports and 
games. Balls are usually 
spherical but can be other shapes, such as ovoid (only in a few special cases).  In most games using balls, the play of the game follows the state of the ball as it is hit, kicked, or thrown by players.
Balls were used in ancient history by the early Egyptians and the ancient Greeks and Romans.
Popular games involving balls include:
In baseball statistics, a ball is a pitch caught outside of the strike zone and not swung at by the batter.  See ball (baseball statistics).
For the use of 
ball in 
mathematics, see 
ball (mathematics).
In modern times balls have been used in machinery. The ball 
bearing is a device used to reduce the 
friction of moving parts in a wide variety of 
machines. Ball bearings use hardened 
steel balls.
For "Christmas ball," see 
Christmas tree.
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