A token is the unit a language model actually reads and writes: a word fragment of a few characters. As a rule of thumb, 1,000 tokens is about 750 English words. Tokens matter commercially because AI APIs bill per token, in and out — every document the model reads and every answer it writes is metered in them.
Token costs are predictable once measured on real volume: a one-month pilot turns the scariest budget line into the most stable one. For most SMB workloads the bill lands between €50 and €500 a month.