Business
Tokens as cost
You usually pay for AI by the token, for both what goes in and comes out.
When businesses use AI through an API, they are typically billed by the token, counting the text sent in and the text generated back. Longer prompts and longer answers cost more, so the bill grows with how much the AI reads and writes. Understanding this helps explain why efficient prompts and shorter outputs can save real money at scale.
For example
Summarizing a huge document costs more tokens, and more money, than answering a one-line question.