Discovered Attack
A discovered attack happens when one piece moves away and opens a rook, bishop, or queen line onto a target.
What to look for
Find one of your pieces blocking a line to an enemy target. Check whether moving that piece opens the line, especially if the moving piece can act with tempo.
Recognize the mechanism
Find a friendly piece between a line attacker and an enemy target. Consider destinations that clear the line while also making a useful threat with the moving piece. Recheck the newly opened ray after the move.
Common practical mistake
Moving a blocker without exposing a meaningful attack is merely a move. Keep the opened line and the moving piece’s own action separate in your calculation.
Training goal
Learn to use hidden line pieces as tactical weapons.