A pin ties a piece to a more valuable piece behind it, making the pinned piece unable to move without exposing something worse. They appear in games at every level and, once a pin lands, the material loss often follows.
A pin is a line-piece tactic -- bishop, rook, or queen -- where a piece cannot move because doing so would expose a more valuable piece behind it to capture. An absolute pin means the piece legally cannot move (it would leave the king in check). A relative pin means moving would lose material but is technically legal.
Our analysis tracks two pin failure modes: Pin Exposed (D), meaning you walked into a pin that cost material, and Pin Miss (O), meaning you had a pin available and did not play it.
Pins are particularly costly because they reduce the mobility of multiple pieces at once: the pinned piece is stuck, and pieces that would normally coordinate with it lose a partner. A single pin can dictate the next several moves of a game.
The pattern recurs predictably: pieces developed to standard squares in common openings are often on the exact lines that opposing bishops and rooks exploit for pins.
Backbox Chess finds these exact patterns in your own games and builds personalized drills from your actual mistakes.
Find pins in my games1. Before moving any piece, check whether it will land on a line with a more valuable piece behind it. Rank, file, and diagonal -- all three axes.
2. Look for your opponent's undefended or overloaded pieces that sit behind pieces you can attack with a bishop or rook.
3. When you see a pin opportunity, calculate whether the material gain justifies the positional trade-off. Not all pins are worth taking.