Editing Pin (chess) (section)

== Types ==
{{Chess diagram 
|tright
|
|  |rd|kd|  |  |  |  |  
|  |  |  |  |  |  |  |  
|  |  |  |  |nd|  |  |  
|  |  |  |  |  |bl|  |  
|  |nl|  |  |  |  |  |  
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|  |ql|  |kl|  |  |  |  
|There is an ''absolute pin'' on the black knight: moving it is not legal since the black king would be exposed to check from the bishop. {{pb}} There is a ''relative pin'' on the white knight: moving it is legal but would allow the black rook to capture the queen.
}}

=== Absolute pin ===
An ''absolute pin'' is one where the piece shielded by the pinned piece is the [[King (chess)|king]]. In this case it is illegal to move the pinned piece out of the line of attack, as that would place one's king in [[Check (chess)|check]] (see diagram). A piece pinned in this way can still give check or defend another piece from capture by the opposing king.

=== Relative pin ===
A ''relative pin'' is one where the piece shielded by the pinned piece is a piece other than the king, but typically is more valuable than the pinned piece. Moving such a pinned piece is legal but may not be prudent, as the shielded piece would then be vulnerable to capture.

=== Partial pin ===
{{Chess diagram 
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|Examples of partial pins
|  |  |  |  |kd|  |  |  
|  |pd|  |  |  |  |  |  
|  |  |  |  |  |  |  |  
|  |  |  |  |  |  |  |  
|  |  |bd|  |qd|  |  |  
|  |  |  |pl|  |  |  |  
|  |bl|  |  |  |  |  |  
|  |  |  |  |rl|kl|  |  
|The black queen is pinned by the white rook, but can still move along the e-file. {{pb}} The white pawn is pinned by the black bishop such that it cannot advance or capture the queen, but it can still capture the bishop.}}

Independently of whether it is absolute or relative, a pin might be a ''partial pin'', in which the pinned piece can still move along the line of the pin, and it might be able to capture the piece that is pinning it, but it cannot leave that line. For example, a rook or queen can be partially pinned along a {{chessgloss|file}} or {{chessgloss|rank}}, or a bishop or queen can be partially pinned along a {{chessgloss|diagonal}}. Capturing the pinning piece can still be advantageous to the pinning player, as in the example diagram (the pinning rook is defended, so capturing it with the queen would lose {{chessgloss|material}}).

A queen can only ever be partially pinned, as it can move in any linear direction, while a knight cannot be partially pinned due to its unique movement. The pawn is a more complex case; due to its limited and conditional movement, whether a pin on a pawn is partial depends on the line and direction of the pin and on whether there are opposing pieces available for it to capture.

It is possible for two opposing pieces to be partially pinning each other.

=== Situational pin ===
{{Chess diagram 
|tright
|Example of a situational pin
|  |rd|  |  |  |  |kd|  
|  |  |pd|  |  |pd|  |pd
|  |  |  |pd|  |  |pd|  
|  |  |  |bd|  |  |  |  
|  |nl|  |  |  |  |  |  
|  |  |pl|  |pl|  |  |  
|  |  |  |  |  |pl|pl|pl
|  |  |  |  |kl|  |  |rl
|White to move. White's knight should not capture the black bishop; otherwise, the rook on h1 is lost.
}}
Sometimes a piece may be considered to be in a ''situational pin''. Like a relative pin, a situational pin does not legally restrict the piece from moving, but moving the pinned piece out of the line of attack can result in some detriment to the player (e.g. checkmate, immediate loss of the game, occupation of a critical square by the opponent, etc.).

Consider the diagrammed position with White to move. The black bishop on d5 is unprotected and White can capture it with 1.Nxd5; however, White should not play the capture or otherwise move the knight, due to the [[Skewer (chess)|skewer]] attack 1...Rb1+ winning White's rook (the king is forced to move, then 2...Rxh1). It can be said that the white knight is "pinned to the b1-square" rather than pinned to a piece.

=== Cross-pin ===
A ''cross-pin'' consists of two or more pins, of any type, on the same piece. As there is only one king per side, only one of the pins can be absolute, but there are otherwise no restrictions on the types of pins involved.