What is System Prompt?
TL;DR
A special instruction that defines an AI model's behavior and role upfront. The design foundation of AI applications.
System Prompt: Definition & Explanation
A system prompt is a special instruction that pre-defines an AI model's behavior, role, constraints, and output format. Set separately from user messages, it controls the AI's responses throughout the entire conversation. Examples include 'You are a Japanese translation expert,' 'Respond in JSON format,' or 'Keep answers under 200 characters.' It is widely used in ChatGPT's Custom Instructions, Claude's System Prompt, and the backends of various AI applications. Designing effective system prompts is a critical factor that significantly impacts AI application quality.