Middlegame

The middlegame in chess refers to the portion of the game in between the opening and the endgame. There is no clear line between the opening and middlegame, and between the middlegame and endgame. In modern chess, the moves that make up an opening blend into the middlegame, so there is no sharp divide. At elementary level, both players will usually have completed the development of all or most pieces and the king will usually have been brought to relative safety. However, at master level, the opening analysis may go well into the middlegame.

Likewise, the middlegame blends into the endgame. There are differing opinions and criteria for when the middlegame ends and the endgame starts (see the start of the endgame). Factors such as control of the center are less important in the endgame than the middlegame. In endgames the number of pieces and pawns is much reduced, though even after queens are traded, one may talk about a "middlegame without queens." The endgame is often said to begin when the kings can safely play an active role.

Theory on the middlegame is less developed than the opening or endgames. Since middlegame positions are unique from game to game, memorization of theoretical variations is not possible as it is in the opening. Likewise, there are usually too many pieces on the board for theoretical positions to be completely analyzed as can be done in the simpler endgames.

The Middle Game in Chess by Reuben Fine lists three major factors in the middlegame: king safety, force (material) and mobility, although not all of these factors are of equal importance. If king safety is a serious issue, a well-executed attack on the king can render other considerations, including material advantages, irrelevant. Material is another important consideration, Fine notes that—if all other things are equal—any material advantage will usually be decisive. According to Fine, a material advantage will usually not give a direct mating attack unless the advantage is very large (a rook or more), rather it can be used as a means of gaining more material and a decisive endgame advantage. The issue of mobility is ensuring that the pieces have a wide scope of action and targets to focus on. The concept is largely strategic in nature, and involves concepts as space, pawn weaknesses (since weak pawns can compel pieces to defensive duties, reducing their mobility), and securing outposts for the pieces.

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