There are many types of AI, each with its own capabilities and limitations. Some of the most impressive AI models to date are Deep Blue, Watson, and AlphaGo. Deep Blue, developed in the 1990s by IBM, famously defeated chess champion Garry Kasparov in a six-game match. Watson, also developed by IBM, is a conversational artificial intelligence that famously competed on the quiz show Jeopardy! and defeated two human champions. AlphaGo, developed by Google DeepMind, is a computer program capable of playing the board game Go at a world-class level, defeating some of the best human players in the world. These AI models are considered some of the smartest because of their ability to perform complex tasks and make human-like decisions.