Absolute pins, relative pins, how to break them, and the classic disaster that happens when you trust one too much.
A pin is chess's version of holding someone's sleeve. The piece is right there, it has places to be, and it cannot go, because a bishop, rook, or queen is glaring straight through it at something more valuable standing behind. Move the front piece and the thing behind gets taken. So the front piece just... stands there. Sometimes for the whole game. It's very sad to watch, especially when it's your knight.
Only the three sliding pieces (bishop, rook, queen) can pin, because a pin needs a line of attack that passes through one piece to another. Knights hop, pawns poke, kings shuffle; none of them can look through anything.
The Absolute Pin: Actually Illegal to Move
When the piece behind is the king, the pin is absolute: moving the pinned piece isn't just a bad idea, it's against the rules, because it would leave your king in check. The pinned piece is temporarily removed from the game while still taking up a square. It's furniture.
See how the calculator recommends breaking this pin
The black rook on e8 pins the knight on e4 to the white king on e1. That knight has exactly zero legal moves. Try to move it and the rules of chess will politely decline.
The Relative Pin: Legal, But It'll Cost You
When the piece behind is anything other than the king (usually the queen), the pin is relative. Moving the pinned piece is perfectly legal; it just means the piece behind gets captured. Most of the time that's enough to freeze the front piece in place anyway.
You've probably already lived inside this position. It arises from one of the most common opening sequences in chess: the bishop comes to g5 and pins the knight on f6 against the queen:
Analyze this opening pin in the calculator
White's bishop on g5 attacks the f6-knight, with Black's queen on d8 waiting behind it on the diagonal. The knight can legally move. It would just prefer not to explain the consequences to the queen.
But "relative" is the key word, and it cuts both ways. Because moving is legal, a pinned piece with a big enough counter-threat can simply ignore the pin. The oldest trap in chess, Légal's mate (named after an 18th-century Parisian master), features a "pinned" knight capturing a pawn, offering the queen for free, and delivering checkmate two moves later while the opponent is still counting their winnings. The lesson: a relative pin is a suggestion, not a law. Before you rely on one, ask what happens if the pinned piece moves anyway.
How to See Pins Coming
Watch your lines, not just your pieces. Before you move anything, glance along the rank, file, and diagonals that connect your king and queen to the rest of the board. Any enemy bishop or rook that reaches one of those lines is a pin waiting to happen, even from across the board, even with pieces in between. The bishop your opponent developed to b5 ten moves ago is not decoration; it's aimed at something.
Beware of self-pinning. The most common way pins appear isn't the opponent creating one. It's you stepping into one. A piece moves, a line opens, and suddenly something behind it is exposed. Make "what does this move uncover?" part of your pre-move checklist.
Count defenders honestly. A piece defended only by a pinned piece is, functionally, not defended. If your knight is protected by a pawn that's pinned to your king, that knight is loose and your opponent knows it.
Breaking a Pin
Pins look permanent. They rarely are. In rough order of preference:
1. Attack the pinner. Pinning pieces are often loosely placed. A pawn push (the classic ...h6 against a bishop on g5) asks the bishop a rude question: retreat, trade, or leave. Any of those beats standing pinned.
2. Block the line. Put another piece between the pinner and the valuable piece behind. The pin dissolves and the front piece is free again.
3. Move the back piece. Step the king (or queen) off the line and the pin evaporates entirely. Often the simplest fix, and beginners forget it exists.
4. Reinforce and shrug. If the pinned piece is defended as many times as it's attacked, the pin wins your opponent nothing. Not every pin needs to be broken; some just need to stop mattering.
Using Pins Yourself
A pin isn't just an inconvenience you inflict. It's a target you create. The winning pattern is pile on the pinned piece: it can't run, so every new attacker you add tips the math further your way. Attack a pinned knight with a pawn and it's usually game over for the knight, because the one thing it wants to do (leave) is the one thing it can't. When you load a position into the move calculator, moves that create a pin get a badge and a plain-English note about what's pinned to what, which is a fast way to learn what the pattern looks like from the winning side.
Quick Answers
What is a pin in chess? A bishop, rook, or queen attacks an enemy piece with something more valuable directly behind it on the same line. The front piece can't move, or shouldn't, because moving exposes what's behind.
Absolute vs relative pin? Absolute: the king is behind, so moving the pinned piece is illegal. Relative: something else valuable is behind, so moving is legal but usually costly, and occasionally brilliant.
How do you break out of a pin? Attack the pinning piece, block the line, move the valuable piece off the line, capture the pinner, or defend the pinned piece enough times that the pin achieves nothing.
Can a pinned piece defend things? An absolutely pinned piece can't legally capture, so anything it "defends" is actually up for grabs. Check whether your defenders are real before trusting them.
