Quick definition · 2 min AI term
System prompt
A system prompt is a standing instruction set at the start of a chat that tells the model how to behave, before you ask anything.
Think of it like
Like the brief you hand someone on day one: tone, rules, and what to do, sitting in the background the whole time.
Example
“You are a terse coding assistant. Always cite file paths and never invent APIs.” Every later answer is shaped by it.
Why it matters
It is the most reliable lever for steering an AI. Role, format, and guardrails live here, separate from your actual question.
Where you’ll see it
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