Glossary · Phase 1 · Building with LLMs
Prefilling
Writing the first words of the model's reply yourself so it continues from there. Newer models reject it; use structured output instead.
Try it now
Keep the user message the same and change only the system prompt. Make the voice playful, or delete the format rule, and compare the replies. If a reply comes back cut off, raise max_tokens, the cap on how long a reply can be.
Learn it properly
System prompts and roles · Set behavior once, separately from the conversation. About 25 minutes.
Other terms from the same lesson
- system prompt: Standing instructions that set how a model should behave for a whole conversation.
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