Castling early is generally a good idea, because it hides your King in the corner. A King that fails to castle early may become stuck in the center, and come under heavy fire from enemy Rooks and Queen. Castling requires first developing the Knight and Bishop (and Queen on the queenside), as the castling move requires empty space between the King and Rook.
Castling decisions often also change the tone of the game. If you castle on opposite side to your opponent, the game is often a fast, attacking game with both sides doing pawn storms against each other’s King. If you castle on the same side as your opponent, the game is more positional and slower.
Related Chess Tactics
Read more about these related chess strategies: