Simplify the following text for a Grade 3 native English-speaking person.
Original: When a player takes three or four moves to accomplish what castling would have accomplished in one move , it is sometimes called artificial castling , or castling by hand .
Simplified: Castling takes one move , and is the only way for a player to move two of his own pieces on the same move . Castling can be done on either side of the board .