Breakthrough: The pawn breakthrough is one of the most important tactical themes in pawn endings. This tactic is based on promoting a pawn to a queen that it can justify the sacrifice of several pawns.
It is the best example for Pawn Breakthrough. Here the white pawns are in opponents camp in the same rank, but the black is close to the white pawns. By using the tactical themes in pawn ending white can win the game.
White to play:
1.b6 cxb6 (1… axb6 2.c6 bxc6 3.a6 unstoppable queen) now the c pawn file is openend but the b7 pawn is not allowing pawn c6 2.a6 bxa6 3.c6 unstoppable queen.