Chess Pins
A piece that can't move — or shouldn't — because of what's behind it.
Absolute vs. relative
The bishop on a1 pins the knight on d4 to the black king on h8, all on the same diagonal. The knight has no legal move at all — a knight can't move along the line it's pinned on, so every square it could jump to would expose its own king to check.
The knight on d5 isn't pinned to the king — it's pinned to the queen behind it on the d-file. That makes it a relative pin: moving the knight is completely legal, it just hands the rook a free queen, so in a real game you'd essentially never do it.
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Pins show up constantly in real games — practice spotting them daily.
Play the Daily Chess ChallengeA pin happens when a piece can't move (or shouldn't move) because doing so would expose a more valuable piece behind it, on the same rank, file, or diagonal, to attack.
There are two kinds, and the difference matters a lot in practice: an absolute pin is against the king and makes the pinned piece completely immobile, by the rules of chess. A relative pin is against anything else — moving the piece is perfectly legal, it's just usually a bad idea.
Absolute pins
When the piece behind the pinned one is the king, the pinned piece cannot legally move at all — not even to capture — because doing so would leave your own king in check, which the rules of chess simply don't allow.
Relative pins
When the piece behind is a queen, rook, or anything else short of the king, the pinned piece can legally move — it just means giving up the piece behind it, so in practice it usually stays put anyway.
When a 'pinned' piece can still legally move
Two situations trip people up: a relative pin (the piece is genuinely free to move, at a cost), and a pin where the pinned piece can move along the pin line itself — for example, a rook pinned to the king along a file can still slide up and down that same file, since doing so never exposes the king.
Attacking a pinned piece and breaking a pin
A pinned piece is a standing target — since it (usually) can't move away, you can pile up additional attackers on it faster than the defender can add support. To break a pin, block the line with another piece, capture the pinning piece, move the king itself out of the line (for an absolute pin), or simply accept the trade if the pinned piece is adequately defended.
Frequently asked questions
What's the difference between a pin and a skewer?
In a pin, the less valuable piece is in front and the more valuable piece is behind it. In a skewer, it's reversed — the more valuable piece is in front and forced to move, exposing the piece behind.
Can a pinned piece ever capture?
An absolutely pinned piece can only capture along the same line it's pinned on (since that doesn't expose the king). A relatively pinned piece can capture anywhere — it's just usually not worth giving up what's behind it.
Is a pinned piece always a bad thing to have?
It's a liability — it can't fully participate in the game and is often a target. Pinning an opponent's piece, on the other hand, is a way to gain a lasting advantage.
Is it free?
Yes. The board is read and analyzed right in your browser, there is no sign up, and you can do it as many times as you like.