A large language model (LLM) is a type of artificial intelligence trained on vast amounts of text to understand and generate human-like language. LLMs power tools like ChatGPT, Claude, and Gemini, and form the foundation of most modern generative AI applications.
How it works
An LLM is a neural network (typically a transformer) with billions of parameters, trained to predict the next token in a sequence. Through that training on large text corpora, it learns grammar, facts, reasoning patterns, and style — which it then uses to answer questions, write, summarize, translate, and generate code. Producing each response is called inference.
Why it matters
LLMs are the engine behind the fastest technology-adoption curve in modern history. ChatGPT alone reached roughly 900 million weekly users by early 2026, and 71% of organizations now use generative AI in at least one function. See our Generative AI Statistics 2026 for the full data.
Related terms: Foundation Model · Generative AI · AI Inference · All glossary entries