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Prompt

Definition

The input text you give to an AI model. Better prompts lead to better outputs.

Why It Matters

Prompts are the only interface to a closed-weight model and the easiest knob to turn on any model. A bad prompt produces a vague answer no matter how powerful the model; a well-structured prompt routinely beats fine-tuning on cost-per-quality terms.

Key Points

  • The three standard roles: system (sets persona and constraints), user (the human turn), assistant (the model's prior turn). Most chat APIs accept all three.
  • System prompts are invisible to end users but heavily influence tone, refusal behaviour, output format, and persona consistency.
  • Prompt caching: providers that support it (Anthropic, Google) charge 90 %+ less for identical prefix tokens sent across repeated calls.
  • XML or JSON tags in system prompts improve instruction-following reliability, most frontier models are fine-tuned on structured prompt formats.
  • Prompt injection: adversarial instructions embedded in documents or tool outputs can override system-prompt instructions, a security concern, not just a quality one.

Example

"Summarise this" returns three to five generic bullet points. "Summarise this article for a CFO in 3 bullets, each ≤15 words, no jargon" returns something usable. Same model, dramatically different output, only the prompt changed.

Common Misconception

Longer prompts are not reliably better. Verbose instructions containing internal contradictions or excessive padding reduce reliability. Precise, minimal prompts that specify format, constraints and persona consistently outperform longer prompts that repeat the same instruction in multiple ways.

Related Terms

  • Prompt EngineeringThe practice of crafting effective prompts to get the best results from AI models.
  • Few-Shot LearningGiving an AI model a few examples in the prompt to guide its output.
  • Zero-Shot LearningAn AI model performing a task without any specific examples, just from its general training.

Prompt on Rewind.ai

Every Rewind.ai tool exposes the prompt, the simpler tools via a guided form, the chat via free-form text. Both compose to the same chat-completion call under the hood.

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Quick Facts

TermPrompt
RelatedPrompt Engineering, Few-Shot Learning, Zero-Shot Learning

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FAQ

Prompt on Rewind.ai is a free AI tool. There's no charge and no sign up needed to start.

Yes. You get 2,500 free tokens per day to use Prompt and every other tool on Rewind.ai. A free account raises that to 5,000 tokens/day. You can buy more starting at $1.

Prompt runs open-source AI models on our GPU servers. Send your request and the result comes back in seconds.

No. You can use Prompt right away without signing up. A free account doubles your daily usage to 5,000 tokens and saves your history.

Anonymous users get 2,500 tokens/day. Free accounts get 5,000 tokens/day. Tokens reset every 24 hours. Each generation costs ~100-5,000 tokens depending on the operation.

Your data is processed on our servers and isn't stored permanently unless you choose to save it. We don't sell or share it.

Yes. Content from Prompt is yours to use for personal or commercial work. The AI models we run are commercially licensed.

Prompt matches the quality of paid services because it runs the latest open-source AI models. The difference is you don't pay per use.

Prompt runs open-source AI models including Qwen 2.5, FLUX and Whisper. We update to newer models as they ship.

Yes. Prompt works in any mobile browser, and the layout adapts to your screen size.

Sign up for a free account to get 5,000 tokens/day, double the anonymous limit. Or buy token packs starting at $5 for 200,000 tokens. See /pricing/ for all options.

Yes. After you generate content, you can download it, copy it, or share it via a unique link. Signed-in users can also view their generation history.

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