Right now, you can do something magical if you own a smartphone. With a few taps of your thumb, you can download a little program called SkinVision that uses the camera to take a picture of moles or other blemishes on your skin. That image is automatically sent via a complicated relay system of cables and satellites to a data server in Europe. A machine, which has been trained on hundreds of thousands of pictures of melanomas over the last few years, analyses that image. It uses a piece of code, employing a clever statistical technique called deep learning, running off a whole bunch of custom-built integrated circuits that were originally designed for playing computer games.