What is AI - specifically what is machine learning?

This entry is part 2 of 3 in the series What is AI once and for all? Artificial intelligence is science fiction. Artificial intelligence is already part of our everyday lives. All those statements are true, it just depends on what flavor of AI you are referring to. Most of us are familiar with the term "Artificial Intelligence." After all, it's been a popular focus in movies such as The Terminator, The Matrix, and Ex Machina but you may have recently been hearing about other terms like "#Machine Learning" and "#Deep Learning," sometimes used interchangeably with artificial intelligence.