What is Token? Plain-English Definition

In more detail

AI doesn’t read text the way you do. Before a model like ChatGPT sees your message, the text gets broken into small chunks called tokens — sometimes a whole word, sometimes just part of one, plus punctuation. A word like ‘unbelievable’ might become three pieces: ‘un’, ‘believ’, ‘able’.

This matters because tokens are how AI is measured and billed. The price of a request, the size of a context window, the speed of a reply — all of it is counted in tokens. When people say a model is expensive, what they really mean is that its tokens are.

📌 See it in action

Type ‘I love pizza!’ and the model might split it into four tokens: ‘I’, ‘ love’, ‘ pizza’, ‘!’. Now paste in a 40-page contract instead: that’s thousands upon thousands of tokens, every one processed and paid for — which is why summarizing a long document costs far more than asking a quick question.

Goes with

Context Window →Inference →LLM →

Now put the vocabulary to work.

Meet the models →Which AI is mine?