Next-token prediction trains a language model to continue a sequence by selecting the most probable token after the tokens already provided. This makes a pretrained model behave like an autocomplete system rather than a naturally conversational agent. section 16.3.1
Prompting changes the likely continuation
A prompt such as “How can I make brownies?” can continue as a forum-style exchange, while “The following brownie recipe is easy to make in just a few steps. You can start by” makes recipe instructions more likely. The model is extending the text pattern, not interpreting the prompt conversationally. section 16.3.1
The practical consequences are straightforward:
- Expect plausible continuation, not automatically useful answers; usefulness depends strongly on the prompt’s surrounding context. section 16.3.1
- Treat each label as the next token in the sequence, shifted one position relative to the input token IDs. section 16.3.2
- During instruction fine-tuning, compute loss for response tokens while excluding the fixed prompt and padded positions. section 16.3.2








