Pawn structure

In chess, the pawn structure (sometimes known as the pawn skeleton) is the configuration of pawns on the chessboard. Since pawns are the least mobile of the chess pieces, the pawn structure is relatively static and thus largely determines the strategic nature of the position.

Weaknesses in the pawn structure, such as isolated, doubled or backward pawns and holes, once created, are usually permanent. Care must therefore be taken to avoid them (but there are exceptions — for instance see Boleslavsky hole below). In the absence of these structural weaknesses, it is not possible to classify a pawn formation as good or bad — much depends on the positions of the pieces. However, the pawn formation does determine the overall strategies of the players to a large extent, even if arising from unrelated openings. Pawn formations symmetrical about a vertical line (such as the e5 Chain and the d5 Chain) can be deceptively similar, but they tend to have entirely different characteristics because of the propensity of the kings to castle on the kingside.

Pawn structures often transpose into one another, such as the Isolani into the Hanging Pawns and vice versa. Such transpositions must be considered carefully and often mark shifts in game strategy.

In his 1995 book, Andrew Soltis classified the major pawn formations into 17 categories, discussed below. In 2015, the book Chess Structures, by Mauricio Flores Rios further studied the subject, subdividing pawn structures into the 28 most important. It is to be noted that for a formation to fall into a particular category, it need not have a pawn position identical to the corresponding diagram, but only close enough that the character of the game and the major themes are unchanged. It is typically the center pawns whose position influences the nature of the game the most.

Structures with mutually attacking pawns are said to have tension. They are ordinarily unstable and tend to transpose into a stable formation with a pawn push or exchange. Play often revolves around making the transposition happen under favorable circumstances. For instance, in the Queen's Gambit Declined, Black waits until White develops the king's bishop to make the d5xc4 capture, transposing to the Slav formation (see below).

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