System Prompt
A high-level instruction that sets a model's role, tone, and rules for a conversation.
A system prompt is a high-level instruction block telling a foundation model how to behave — its persona, tone, scope boundaries, and rules to follow throughout the session. Unlike a user message, which changes each turn, it persists across the conversation and is usually invisible to the end user. In Amazon Bedrock you set it at the API call level, and it works alongside Guardrails for Amazon Bedrock, a Bedrock feature enforcing content policies. The exam trap is confusing it with a user prompt: role and constraint definitions belong in the system prompt, not in each user turn.
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