Even as a person who knows totally nothing about Go, I found the Google DeepMind challenge match between AlphaGo and Lee Sedol very exciting. I actually read a book about artificial intelligence a few months ago. There it said that AI is already a great chess player and later might be a great Go player as well. After hearing the news of 3 consecutive wins of AlphaGo, I was surprised at how fast AI was developing.
So how was AlphaGo capable of winning against a professional 9-dan player? It uses "machine learning" and "tree search techniques" according to Wikipedia. Machine learning is literally the ability of a program to learn by itself and make new rules at certain circumstances. Tree searching? It's actually something we do every single day – making choices to find the answer. Take a look at the diagram below.