Pin

A pin happens when a piece is attacked along a rank, file, or diagonal, and directly behind it on that same line sits a second, more important piece it isn't allowed to move away from. The pinned piece is still on the board and still technically "yours," but for as long as the pin holds, it can't do its job — it can't capture, can't defend something else across the board, and in the worst case can't move at all.

Absolute pins vs. relative pins

There are two genuinely different situations that both get called a pin, and mixing them up leads to real calculation errors. An absolute pin is against the king: moving the pinned piece would expose the king to check, which makes it illegal — the piece is frozen by the rules of chess itself, not just by good judgment. A relative pin is against anything else valuable — a queen, a rook, an undefended piece — and moving the pinned piece is completely legal, just costly. A knight relatively pinned to a queen can still move, but if it does, the queen falls. Absolute pins are unbreakable until the line is blocked or the attacker is dealt with; relative pins can be broken any time the defender is willing to pay the price.

The geometry that tells you a piece is pinnable

Before you can use a pin, you have to notice one is available, and that means training your eye for a specific shape: an enemy piece that has not moved off the same rank, file, or diagonal as its own king or another valuable piece, reachable by your bishop, rook, or queen. Knights are pinned constantly because they're developed early and often just sit in front of the king on the same diagonal or file without the player noticing. The single most useful habit is to ask, every time you consider developing a bishop or rook: does this square also happen to line up an enemy piece with something bigger standing behind it? That question, asked on every developing move rather than only when you're specifically "looking for tactics," is what turns pins from something you occasionally stumble into a pattern you actively create.

Turning a pin into something concrete

A pin by itself doesn't win material — it just removes a defender from the game for a while. The follow-through is what matters: pile up more attackers on the pinned piece than the defender can add protectors, or use the tempo the pin buys you to improve your position elsewhere while the opponent is stuck untangling it. In the example above, the pin never gets "exploited" in the sense of extra attackers arriving — instead, the defender is forced to spend a move breaking the pin, and that move alone leaves the piece undefended. That's a common and easy-to-miss pattern: the pin doesn't need to be permanent to win material, because escaping it can be exactly as costly as staying in it.

When a pin is a wasted move

Not every pin is worth creating. A pin only matters if the defender genuinely can't afford to break it, or if breaking it costs them something real. Pinning a knight to a rook in the middlegame, when the rook was going to move anyway or the knight has nothing useful to do regardless, spends a tempo for no gain. Worse, an inexperienced player will sometimes pin a piece to their own king by accident on the wrong side of the board — for example, over-committing a bishop to a diagonal that only becomes a genuine threat to your own position once the center opens. Before committing to a pinning move, check what the pinned piece was actually going to do if left alone; if the honest answer is "nothing important," the pin isn't accomplishing anything.

Breaking a pin as the defender

If you're the one being pinned, you have three real options: block the line with a third piece, remove the attacker (trade it off or chase it away), or move the piece behind the pinned one so the line no longer matters. Interposing a pawn or minor piece between the attacker and the pinned piece is often the cheapest fix, provided the new blocker isn't itself more valuable to lose. Sometimes the best answer is simply to accept the pin and play around it — a knight pinned to a rook that has no urgent need to move isn't actually costing you anything, and "fixing" a pin that isn't hurting you can waste more time than living with it.

A pin only wins material outright when the pinned piece is truly stuck — if the piece in front is forced to move by check rather than merely forbidden to, you're looking at a skewer instead, which is worth telling apart from a pin because the follow-up technique is different. Openings that develop bishops early onto active diagonals, like the Italian Game, are exactly where pinning opportunities tend to appear first.