How neural networks work--and why they've become a big business – Ars Technica

The last decade has seen remarkable improvements in the ability of computers to understand the world around them. Photo software automatically recognizes people's faces. Smartphones transcribe spoken words into text. Self-driving cars recognize objects on the road and avoid hitting them. Underlying these breakthroughs is an artificial intelligence technique called deep learning. Deep learning is based on neural networks, a type of data structure loosely inspired by networks of biological neurons. Neural networks are organized in layers, with inputs from one layer connected to outputs from the next layer.