The system prompt gives the model a fixed frame, such as instructing it to act as a helpful customer-service assistant or to respond only in English. Unlike individual user prompts, it remains active across the whole session and usually carries higher priority. Developers use system prompts to set guardrails and standardize behavior. A well-written system prompt is the foundation for consistent AI applications.
System Prompt
A system prompt is a high-level instruction that defines an AI model's behavior, role, and tone for the entire conversation. It is processed before the actual user inputs.