What an Agent Actually Is

Know the Vocabulary

This lesson uses the terms below many times. Read them once now, and come back here when a later section needs one.

• Large language model (LLM): A model that reads text and writes text. Chat assistants and agents are built on LLMs.
• Token: A short word or a piece of a longer word. Models read and write text as tokens, and providers charge by the token.
• Tool: A function the model may ask the system to run, such as looking up an order. The model only asks, and ordinary code runs the function.