Large language model

A large language model is an AI system trained on huge amounts of text to predict the next word, which lets it write, summarise, translate and answer questions.

In practice: You type a request, the model turns it into tokens, and it generates a reply one token at a time based on patterns learned in training. ChatGPT, Claude and Gemini are all built on large language models. Most AI writing, chat and coding tools in the directory use one underneath, often a model licensed from one of the big labs rather than their own.

Why it matters when picking a tool

Many tools are a layer on top of the same few models, so ask which model a tool uses and whether you can switch. The layer on top is what you pay for: templates, integrations, team features. If a tool adds nothing over the model it wraps, the model's own app is usually cheaper.