Machine Learning is a big scary term for something that can be explained very simply. When you see someone you've seen several times before, you recognize them. In the same way, Google's computers recognize photos of your face because they all look similar. Google's machines are able to learn - that's just one piece of the puzzle. Google has announced a system called TensorFlow, a machine learning system that Google will be using soon (in place of their old system being used today), and they'll be making it open source, too.