Why is the castling move in chess?

Answer 1

It gets the king in a corner behind a row of pawns with a rook in a stronger position.    It makes the game harder to play as you have to assume the other guy is going to castle.   You could set up for a king side castle and he goes and does a queen side and screws up your whole game plan. 

Answer 2

I have beating the person more times when my opponent decides to castled.

Answer 3

Castling was added to European chess in the 14th or 15th century. It moves a King to a safer position & develops a Rook rapidly.