System Prompt

Definition

The foundational, hidden instruction set given to an LLM before the user even starts chatting. It defines the AI's overarching persona, rules, boundaries, and formatting constraints.

Explain Like I'm New

The AI's 'Prime Directive'. It runs in the background. If the System Prompt says 'You are a pirate', then no matter what the user asks, the AI will answer using pirate slang.

Real World Example

When you build an AI customer support bot, you write a System Prompt: 'You are a polite support agent for Acme Corp. NEVER offer refunds. Keep answers under 50 words.' The user never sees this prompt, but it controls all of the AI's behavior.

Common Use Cases

•AI Application Development
•Guardrails
•Persona design

Interview Questions

basic

Does the end-user (the customer) normally see the System Prompt?

intermediate

If a User Prompt explicitly tells the AI to ignore the rules, but the System Prompt tells the AI to follow the rules, what happens?

Flash Cards

Question

Does user see it?

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Answer

No. It is configured by the developer on the backend and remains hidden from the chat interface.

Question

System vs User override?

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Answer

This is called a 'Prompt Injection' attack. Historically, the AI would get confused and often obey the User. Modern models are heavily trained to treat the System Prompt as the ultimate authority, rejecting the user's attempt to break the rules.