A situation when a piece or a pawn cannot or is forbidden to move because it could expose the king for an attack or would expose a more valuable piece behind it to capture.
In the following example Qa3 and Re7 are pinned.
ECHESSPEDIA
Quotes of the Day
Agon was just sold for one pound and the reputation of Ilyumzhinov’s FIDE is worth even less than that.
Garry Kasparov 2014
Tactics is what you do when there is something to do; strategy is what you do when there is nothing to do.
Savielly Tartakower
Some players lose ability to think independently and rely on computers completely.
Lajos Portisch 2012
Some people think that if their opponent plays a beautiful game, it’s okay to lose. I don’t. You have to be merciless.
Magnus Carlsen
Fischer wanted to prove that all world championship games after his victory were prearranged. He did not convince me.
Vishy Anand 2008