AI Glossary
What is an LLM?
LLM (large language model): An LLM — large language model — is an AI system trained on enormous amounts of text to predict the next word, and through that to write, summarize, translate and reason.
In plain English
Think of it as autocomplete taken to its logical extreme. To get good at predicting the next word across most of the public internet, the model is forced to absorb grammar, facts, styles of argument, even some reasoning. The result is a system that can continue any text you start — and "continuing text" turns out to cover an astonishing range of useful work.
Why it matters
- ChatGPT, Claude and Gemini are all LLMs — same family, different training
- An LLM is not a database: it has no list of facts to look up, only patterns — which is why it can be confidently wrong
- Quality scales with training data, model size and training technique
A concrete example
Ask an LLM to "decline this meeting politely" and it writes a natural email instantly — not because it stored your situation, but because it has seen millions of polite declines and knows the shape of one.
Related terms
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