A neural network is a machine learning model loosely inspired by the brain, made of layers of connected "neurons" that adjust their connection strengths to learn patterns from data.
A neural network takes in data (like pixel values of an image), passes it through layers of interconnected nodes, and produces an output (like "this is a cat"). Each connection has a "weight" that the network adjusts during training.
During training, the network makes a prediction, compares it to the correct answer, and calculates how wrong it was (the "loss"). It then adjusts its internal weights slightly to reduce that error, repeating this process over thousands or millions of examples until it gets consistently accurate.
Last reviewed: September 2026