Token

Token means two different things and you'll meet both.

The first is a string that proves who you are, an access token. Same idea as a key, same handling as any other secret: treat it like a password.

The second is how an AI model's usage is counted. Models read and write in small chunks, roughly the size of a short word, and those chunks are tokens, every message you send and every reply back counts.

What surprises people is that a long conversation isn't free just because you stopped attaching files: the whole thing is re-read each turn. See what this costs today.