System prompt: The Founder's Guide to AI Fundamentals

A system prompt is a set of instructions given to a large language model (LLM) at the start of a conversation to shape how it behaves. A system prompt sets the role, personality, and guardrails for the LLM. For example, it can tell the model to act like a helpful tutor, an email security filter, or a playful character.

End users usually don't see the system prompt. It operates behind the scenes.

Is a system prompt only applicable to LLMs?

Yes and no. The term system prompt applies specifically to LLMs. The concept of a prompt that configures or constrains a system at runtime however, is broader and not limited to LLMs.

For example, in reinforcement learning, configuration files are used to set goals, constraints, or policies before they start interacting with an environment. Other related terms used in AI for setting parameters are initialization, bootstrapping, or hyperparameter.

See related: Supervised learning: The Founder's Guide to AI Fundamentals