Watch: System Prompt
The standing instruction at the top of a model's context that sets its role, rules, and behaviour for a whole conversation, given priority over user messages and usually hidden.
Transcript
At the very top of an AI model's conversation sits the system prompt. This is a set of standing instructions that defines the model's role, rules, and behavior. It tells the virtual assistant who it is, how to behave, what tone to use, and what it is allowed to do.
Unlike the messages you type into a chat, the system prompt usually stays hidden. It persists throughout the entire conversation, remaining active even as user messages come and go. Because the model gives this prompt priority over regular messages, it serves as the ultimate guardrail. Any attempt by a user to override these rules is known as a prompt injection.
Designing this environment is a practice called context engineering, and the system prompt is its most privileged tool. It shapes how the model answers questions, represents brands, and cites its sources, ensuring the AI stays on track from start to finish.