ModelRefs / User Message — AI Glossary
User Message — AI Glossary
A message in the chat completion format carrying the human turn of a conversation, processed by the model as a request to respond to.
Overview
User messages alternate with assistant messages in the chat thread. They may contain text, images (for multimodal models), tool call results, or file attachments. In multi-agent systems, the user role is often occupied programmatically by orchestrators injecting tool results or instructions.
Reference details
| Topic | prompting |
|---|---|
| Also known as | human turn, user turn |
| Last reviewed | 2026-06-24 |
Related terms
Commonly confused with
One of three roles, and the role is a weighting, not a security boundary. System messages carry the most authority, user messages the request, assistant messages the model's prior turns. The trap is assuming the user role means a human typed it — retrieved documents and tool output are frequently placed there too, and the model treats instructions inside them as instructions.
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Frequently asked questions
What is User Message?
A message in the chat completion format carrying the human turn of a conversation, processed by the model as a request to respond to.
Is User Message the same as human turn?
Yes — human turn, user turn are common aliases for User Message.
What concepts are related to User Message?
Closely related concepts include system message, assistant message, message threading.