# System prompt

URL: https://onlykin.ai/glossary/system-prompt
Updated: 2026-06-04
Category: Prompting

## Definition

A system prompt is high-priority instruction text that guides how an AI model should behave before it reads the user's message.

## Quick Answer

In AI roleplay, the system prompt can set writing style, role boundaries, response length, point of view, safety rules, and how strongly the model should stay in character.

## Plain Language

It is the instruction layer the model sees before the conversation. For roleplay, it helps prevent the character from sounding like a generic assistant.

## Why It Matters

System-prompt searches capture users trying to fix robotic replies, character drift, and prompt reliability.

## OnlyKin Angle

OnlyKin should keep most system-prompt complexity behind the product while teaching creators how style and example dialogue shape output.

## Related Terms

- Example dialogue: https://onlykin.ai/glossary/example-dialogue
- Character card: https://onlykin.ai/glossary/character-card
- Context window: https://onlykin.ai/glossary/context-window
- Token: https://onlykin.ai/glossary/token

## Sources

- [OnlyKin prompt-writing guide](https://onlykin.ai/blog/how-to-write-ai-roleplay-prompts) - Used for roleplay-specific system prompt advice.
- [OpenAI prompt engineering guide](https://platform.openai.com/docs/guides/prompt-engineering) - Used for the general principle that instructions and examples shape model outputs.