Core Concepts
Tokens
The chunks of text AI models read and produce — usually 3–4 characters each.
Also known as: token,AI tokens
A token is the basic unit of text an AI model reads and produces. It is not exactly a word — it is more like a chunk of characters. The word "humanizer" might be one token; "hallucinations" might be two; very rare words get split into many. As a rough rule, 1 token = 4 characters of English, or roughly 0.75 words. So 1,000 tokens is about 750 English words. Tokens matter because that is the unit you are billed in. When OpenAI charges "$5 per million input tokens" for GPT-5, that is what it means. Most API responses run in the hundreds-to-thousands-of-tokens range; document analysis can hit hundreds of thousands.
