Deep Blue defeated Garry Kasparov at chess in 1996, demonstrating that computers could beat the world's best human players at strategic games. In 2011, IBM's Watson computer system defeated human champions on the game show Jeopardy, showing machines could understand natural language. Google's AlphaGo program defeated Lee Sedol, one of the world's top players, at the ancient Chinese board game of Go in 2016, achieving a milestone in artificial intelligence by conquering a game more complex than chess.