System prompt

The standing instructions an AI is given before you say a word — its job description, its rules, its manners. You never see it and you can't change it, but it shapes every reply you get.

The briefing a new receptionist gets on day one, before the first call comes in: who we are, what to say, what never to promise, when to fetch someone senior.

Why it matters: this is the answer to "why is this chatbot like this?" When a supplier's AI keeps refusing something reasonable, invents a policy they don't have, or talks in a voice that isn't theirs, it's almost always the system prompt rather than the AI being broken. It's a setting, and someone on their side can change it in an afternoon.

Which is why the phrase is worth knowing: it turns a shrug into a specific request — what's in the system prompt, and can you change that line of it? You will never write one. You will very likely have cause to ask about one.

Related: Prompt · Guardrail