What is Large Language Model (LLM)?

A large language model (LLM) is a type of AI system trained on billions of words of text — web pages, books, code, academic papers, and more. This training allows LLMs to predict and generate coherent text, answer questions, summarise documents, write code, and perform complex reasoning tasks.

The most well-known LLMs include OpenAI's GPT-4, Anthropic's Claude, Google's Gemini, and Meta's Llama family. Each has different strengths, pricing models, context window sizes, and appropriate use cases.

For businesses, LLMs are the engine underneath most AI tools — from customer service chatbots to document analysis to code generation. You access them via APIs, paying per token (roughly per word) processed. Understanding their capabilities and limitations helps you make better decisions about where AI investment will and won't pay off.