The unit models read and write in — roughly three-quarters of a word in English. "Orchestration" is about four tokens. Models are priced per token, in and out, like a taxi meter running in both directions.
Why it matters: tokens are the currency of everything here. Cost, speed, and the model's "attention span" are all measured in them.
A separate security token (a login pass for software) is a different thing entirely that shares the word — both appear constantly in agent work.