01In plain English
A large language model is an AI model trained on a very large amount of text, which it uses to predict and generate language. GPT, Claude, Gemini and Llama are families of LLMs. Most AI writing, chat and coding tools are built on one of them.
02Why it matters when you are choosing
Many tools are a layer on top of someone else's LLM. Knowing which model a tool uses tells you a lot about its quality, its limits and where your data goes.
03What to check
Ask the vendor
Check which model or models the tool uses, whether you can choose, and whether your data is passed to the model provider.