Large language model (LLM)
A large language model (LLM) is an AI model trained on vast amounts of text to predict and generate language. It powers chatbots, code assistants and the AI answer engines that increasingly sit between people and websites. The GPT, Claude and Gemini families are well-known examples.
A large language model is the engine behind most of what people now call "AI". It takes a prompt and produces text, code or structured output by predicting what should come next, one token at a time.
For most product teams the practical point is this: you rarely train your own LLM. You build on top of an existing one through an API and spend your effort on the parts that make it useful and reliable, the prompt, the data you feed it, and the guardrails around it. That work is what a good AI product engineer actually does.
