> For the complete documentation index, see [llms.txt](https://docs.n8n.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.n8n.io/connect/create-nodes/build-your-node/reference/base-files/programmatic-style-execute-method.md).

# Programmatic-style execute method

The main difference between the declarative and programmatic styles is how they handle incoming data and build API requests. The programmatic style requires an `execute()` method, which reads incoming data and parameters, then builds a request. The declarative style handles requests using the `routing` key in the `operations` object.

The `execute()` method creates and returns an instance of `INodeExecutionData`.

{% hint style="warning" %}
**Paired items**

You must include input and output item pairing information in the data you return. For more information, refer to [Paired items](/connect/create-nodes/build-your-node/reference/item-linking.md).
{% endhint %}