Opening the diagonal
Opening a diagonal is an important tactical tool.
When between your bishop and the opponent's king or other piece or between your queen and the opponent's king or other piece stands one of your pawns or pieces and you move it, then you opened the diagonal. Your bishop or queen can attack the opponent's piece.
I would like to show you an example about it from a game which I played on chess.com. It was part of a simultanius play when I played against many players.
I show the situation as a puzzle.
Please try to calculate a few minutes to find the right moves before you look the solutions!
In the analysis I found 2 possible checkmates. I hope you like them:
Be aware of the possibilities of the opening of the diagonal for your or for the opponent's bishops and queens!