A large language model is a neural network trained on massive text collections to predict and generate language. 'Large' refers to billions of parameters. LLMs power chatbots, writing tools, code assistants, and most current AI agents.
LLMs are the engine of the current AI wave. Understanding that they model language statistically — rather than 'knowing' like a database — explains both their fluency and their failure modes.
The same LLM can summarize a paper, translate it, and answer questions about it — three tasks, one model, driven by different prompts.