Artificial neural networks are inspired by biological neural networks, such as the brain. Such systems learn tasks by considering examples, generally without task-specific programming. For example, in image recognition they might learn to identify images that depict cats by analysing sample images that have been manually labelled as “cat” or “no cat” and by using the results to identify cats in other images. They do this without any a priori knowledge about cats, e.g. that they have fur, tails, whiskers and cat-like faces. Instead, they evolve their own set of relevant characteristics from the training material that they process.