Passed pawns are pawns that do not have opposing pawns in front of them on adjacent files. A passed pawn can become a serious advantage as it is quite hard to block. The opponent has to involve his pieces to prevent a passed pawn from promoting. This tactic has obvious weakness, as blocking pieces would become passive and limited to the defensive job.
Passed Pawns in the Middle Game
A passed pawn may give a very solid advantage in the middle game. A great player, David Bronstein, used to recommend advancing it as far as possible, where it will destroy the opponent’s piece coordination and connection between the flanks. But at the same time, we should make sure that the passed pawn is very well protected. The most solid way to insure a passed pawn is to protect it with another pawn. Such pawns are called “Protected Passed Pawns.”
Passed Pawns in the Endgame
A passed pawn becomes most dangerous at the endgame. If only two pieces are left and one of them is busy with stopping the passed pawn, it becomes much more visible in the endgame than during the middle game when there are a lot of other pieces on the board. The range of the blocking piece is limited and it can’t help in defense of outlying territory.
A passed pawn almost always guarantees victory in the pawn endgames, even if it is not protected. After some time the opponent will come to take it with his king and will lose too much time, while our king will start attacking his pawn structure on the opposite side. We can see this typical winning plan on the board.