Turing had the idea that to get a real AI, you'd have to build a system that learned. You'd build a child, and it would learn to be an intelligent adult.
Bill Gates said that AI is now called Machine Learning (in about 2007). I don't agree, but it states the importance of Machine Learning in AI.
Big data is big. Google is built on it. More and more, machine learning systems play a part in industry. (There are a lot of jobs in it.)
The idea is that a system learns to do a task. This can be supervised, unsupervised, or some place in between.