What is tilt?

Ive seen alot of discussion of "tilt." someone fill me in on whast exactly this is.

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"Drum machines have no soul!"

Tilt is a negative state of mind that can occur to a poker player. It is brought on usually by a bad beat or bad play or when a player is down alot of money. Because the player is losing, he starts playing poorly because he feels like he desperately needs to win his money back. Tilt may cause a player to play too loose, or to bluff at a the wrong time.