The research purpose of Artificial Intelligence (AI) is to expand human intelligence by exploring the essence of intelligence-to make intelligent agents listen (speech recognition, machine translation, etc.), see (image recognition, character recognition, etc.), speak (speech synthesis, man-machine dialogue, etc.), think (man-machine game, expert system, etc.) and learn (knowledge representation, machine learning, etc. A classic definition of AI is: "Intelligent agents can understand data and learn from it, and use knowledge to achieve specific goals and tasks. (A system’s ability to correctly interpret external data, to learn from such data, and to use those learnings to achieve specific goals and tasks through flexible adaptation)”