What is a System Prompt?
A system prompt is the standing instruction an AI assistant receives before any user input: who it is, how to format answers, when to search the web, how to cite sources. Users never see it, but it shapes every answer, including how brands get recommended and attributed.
Why it matters for AI visibility
System prompts decide behaviors GEO cannot touch directly: whether the assistant searches before answering, how many sources it cites, whether it hedges recommendations. When a platform changes its system prompt, answer patterns shift overnight without any model retrain. It is one reason monitored visibility can move when nothing about your content changed.
Related but different
The user's own message is the prompt. Retrieval instructions and tool definitions often live alongside the system prompt. None of this is editable from the outside; what you control is the content the retrieval step finds and the facts the training data learned.