Ever wondered what machine learning was and still failed to understand it no matter how much you read? Then this neat visual introduction to the topic should do just the trick.
Using a data set about homes, the site does an honestly amazing job of describing how it's possible to teach computers to discern between different types of things and classify them -- ultimately even making predictions. So, using that housing data, you'll see how it's possible to use statistical models to distinguish homes in New York from homes in San Francisco. It's like magic, only it's maths and science. Go take a look.