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
In one game it is too difficult to play both for win and draw simultaneously.
Mihail Tal 1969
Chess…gives students an opportunity to think at a different level.
Dr. Chad Witherspoon 2014
Despite the ugliness of his decline, Bobby Fischer deserves to be remembered for the great things he did for chess and for his immortal games.
Garry Kasparov 2004
Everything is very concrete nowadays. The computer often gives unnatural moves which are correct, but sometimes hard to remember. You know a line is correct, but then your forget something and lose terribly.
Daniel Stellwagen 2010
It’s always more difficult to hold the title than to get it.
Vladimir Akopian 2012