> For the complete documentation index, see [llms.txt](https://tailwindsdocs.innovativesol.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tailwindsdocs.innovativesol.com/readme/chatflows/llamaindex/engine/query-engine.md).

# Query Engine

A query engine serves as an end-to-end pipeline enabling users to ask questions about their data. It receives a natural language query and furnishes a response, accompanied by relevant context information retrieved and passed to the LLM (Large Language Model).

<figure><img src="/files/csILGouRDp1GRhzFuu68" alt=""><figcaption></figcaption></figure>

## Inputs

* Vector Store Retriever
* [Response Synthesizer](/readme/chatflows/llamaindex/response-synthesizer.md)

## Parameters

| Name                    | Description                                                         |
| ----------------------- | ------------------------------------------------------------------- |
| Return Source Documents | To return citations/sources that were used to build up the response |

## Outputs

| Name        | Description                   |
| ----------- | ----------------------------- |
| QueryEngine | Final node to return response |