The beginning phase of the game, roughly the first dozen moves, but it can extend much farther. In the opening players set up their pawn structures, develop their pieces, and usually castle. The opening precedes the middlegame.

The beginning phase of a game, usually the first 10-15 moves. It is characterized by rapid development of forces, control and/or occupation of the centre, and getting the king to safety. The real purpose of the opening is to create an imbalance in the enemy's camp, and development of pieces to exploit this imbalance.