Abstract: In March 2016 and May 2017, the computer AlphaGo defeated two top professionals Lee Sedol and Ke Jie by 4:1 and 3:0, respectively, in the game of Go. In 2015 the Go community still estimated the computer's ability to be fairly limited, but now admit that humans are completely defeated. We shall introduce important algorithm concepts such as Monte-Carlo tree search, policy network, value network, reinforcement learning, etc., review the breakthroughs of the computer Go algorithm that led to its final victory over humans, and discuss the impact of artificial intelligence on Go and society in general.