A neural network is a graph of simple units ("neurons") that take numbers in, apply weights, and pass numbers out. Layers of neurons process information step by step. LLMs are very large neural networks trained to predict the next token in text; that ability underlies chat, summarization, and tool use.
Layers and neurons (concept)
Each "neuron" takes inputs, applies weights, and passes a value forward. Many layers = deep learning. LLMs are huge neural nets trained on text.
In one line
More layers and more neurons = more capacity to learn complex patterns; that’s why modern LLMs have billions of parameters.