Neural Network

It's a computing structure inspired by the way brain cells (neurons) exchange signals. Simple computing units—each one taking numbers, multiplying them by weights, and passing them to the next layer—are connected together by the millions or even trillions.

The phrase "modeled after the brain" is more of a metaphor—the actual workings differ a lot from a real brain. But the core idea, that connecting simple parts in massive numbers can produce surprising abilities, is neural networks' lasting legacy, and today's large language models are the extreme expression of that idea.