Backward pawn

In chess, a backward pawn is a pawn that is behind all pawns of the same color on the adjacent files and cannot be safely advanced. In the diagram, the black pawn on the c6-square is backward.

Disadvantages

Backward pawns are usually a positional disadvantage since they are difficult to defend. Also, the opponent can place a piece, usually a knight, on the hole in front of the pawn without any risk of a pawn driving it away. The backward pawn also prevents its owner's rooks and queen on the same file from attacking the piece placed on the hole.

If the backward pawn is on a half-open file, as in this case, the disadvantage is even greater, as the pawn can be attacked more easily by an opponent's rook or queen on the c-file. Pieces can become weak when they are devoted to protecting a backward pawn, since their obligation to defend the pawn keeps them from being deployed for other uses.

In practice

Modern opening theory features several openings in which one of the players deliberately incurs a backward pawn in exchange for some other advantage such as the initiative or better development. An excellent example is the Sveshnikov Variation of the Sicilian Defence.