Grandmaster Gregory Kaidanov explained the simple tactical motif of the pin to children at the Lexington Chess Tournament on December 12, 2009. The position used is from analysis of the game Prasad vs. Kaidanov played in Calcutta in 1988. Watch the video and replay the game with the grandmaster's analysis after the fold.
Check out the game score with the analysis that Grandmaster Kaidanov demonstrated. White doesn't want to play 12. 0-0 or trouble will follow.