A way to make AI answer with fixed fields and formats.
Structured output is a lunch-order form for AI. It fills the boxes, instead of writing a poem about pizza.
It makes answers come back in set fields. Apps use it for forms, tool calls, and clean handoffs.
Function-calling
Structured output often lines up the arguments first, then Function-call runs the tool.
API
A stable output shape helps an API or backend catch the result cleanly.
Prompt
A Prompt often names the fields, types, and return format.
LLM
Structured output works on the LLM answer, so the model acts neater, not smarter.