A pin immobilizes an enemy piece by lining it up with a more valuable piece standing behind it, on the same rank, file, or diagonal. As long as the pinned piece stays put, it’s unwillingly shielding the piece behind it, and if it moves, that more valuable piece falls.

Absolute pins and relative pins

There are two kinds of pin. An absolute pin immobilizes a piece against the king: the rules of chess flatly forbid moving that piece, since doing so would put the king in check. A relative pin immobilizes a piece against another valuable piece (usually the queen): moving the pinned piece is still legal, but it comes at a steep cost.

Absolute pin: the black knight cannot move at all, since any knight move would expose the king to the white rook.

In this position, the knight on e5 is completely paralyzed: no knight move is legal, because each one would expose the black king to the white rook.

The classic example: the Ruy Lopez pin

The bishop on b5 lines up against the c6-knight and the black king: the pin looms on the diagonal.

In this opening, White’s bishop settles on the diagonal running from the c6-knight all the way to the black king on e8. At this stage, the knight isn’t actually immobilized: the d7-pawn still closes the diagonal toward the king, and the knight keeps every legal move it has. This is strategic pressure, a pin in the making rather than an absolute one: as soon as the diagonal opens, moving the knight will become illegal or very costly. It’s still the best-known picture of a pin in all of chess, used in nearly every beginner course.

Exploiting or escaping a pin

To exploit a pin, pile up attackers on the pinned piece: it can’t run away, so every new attacker adds pressure until it falls. A pawn, a knight, or any other piece can all join the attack against the immobilized victim.

To defend against a pin, you have a few options: block the line between the attacker and your pinned piece, chase the attacker away with a pawn, or simply live with the discomfort if the pinned piece isn’t under direct threat yet. In many openings, a common way to neutralize an annoying pin is playing a6 to chase the bishop away before it becomes dangerous.

Frequently asked questions

Can an absolute pin really stop you from moving a piece?

Yes, completely. In chess, you’re not allowed to play a move that leaves your own king in check. A piece pinned against the king therefore cannot legally make any move that takes it off that line, even to capture an enemy piece elsewhere.

Can a pinned piece still capture something?

It depends on the direction. A piece under an absolute pin can sometimes capture if the capture stays on the line of the pin (a rook taking the piece that pins it along its file, for example). A pawn, though, only captures diagonally: pinned along its file, it can never capture; pinned along a diagonal, it can sometimes take the very piece that pins it. Any move that leaves the pin line remains illegal.

Is a relative pin actually dangerous?

Yes, even though moving the piece is legal. In a relative pin, moving the pinned piece exposes the more valuable piece behind it to immediate capture. In practice, players almost always prefer to keep the piece in place rather than lose material.