The pawns are the eight foot soldiers that start in front of the pieces. A pawn can move forward either one or two squares on his first move. On every move taken after that the pawn can move forward only one square. Unlike the other pieces in the game, the pawn can only move forward, never backward.
When capturing an enemy piece the pawn moves forward one square diagonally either left or right. He completes the capturing maneuver on the adjacent file where his victim had been. The pawn cannot capture a piece directly in front of him. He is blockaded by such a piece.
If a pawn reaches the final rank on the other side of the board he is almost always promoted to a Queen. Occasionally, if in the position it is more advantageous, the pawn can be under-promoted to a Rook, Bishop or Knight. Usually though chess basics will call for a Queen.