Backward pawn
In chess, a backward pawn is a pawn that is behind all pawns of the same color on the adjacent 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 because they are unable to be defended by other pawns. Also, the opponent can place a piece—usually a knight, but it can also be a bishop or a rook—on the in front of the pawn without any risk of a pawn driving it away; such a square is called an outpost and can be very powerful, especially if there is no practical way to trade it off with another piece. 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, the disadvantage is even greater because the pawn can be attacked more easily by an opponent's rook or queen on the 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.
The successful of a backward pawn can be disastrous for its owner. When a backward pawn is lost, its neighbors may become isolated, making them vulnerable, and the king's safety could be put in jeopardy, due to the opponent's pieces now having a clear path to move closer to it.
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 initiative or better. An example is the Sveshnikov Variation of the Sicilian Defence.After the moves 1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 '5. Nc3 e5!? 6. Ndb5 d6, Black has a backward pawn on d6, but White now has to endure a displacement of his knights and an undermining of his after 7. Bg5 a6 8. Na3 b5 9. Bxf6 gxf6 10. Nd5 10... f5! 11. c3 Bg7', and so on.