In 1959, Arthur Samuel, an artificial intelligence researcher and inventor of the first self-learning drafts computer program, coined the term “machine learning” and defined it as a process whereby computers were able to show behavior that wasn't been explicitly programmed. 

Machine learning is a subclass of artificial intelligence: in addition to it, it includes robotics, and much more. Machine learning itself includes various methods, in particular, working with neural networks, which are now so popular.