# Nodes

Nodes read, process, and save data, or control execution order. Find steps by category below, or write your own logic with a Python custom operator. For Start and End, see [Create and orchestrate](../create-and-edit.md).

## Browse by category

| Category | Purpose |
| --- | --- |
| [AI processing](ai-processing/index.md) | Parse content, extract information, and build indexes |
| [Data IO](data-io/index.md) | Read data and save results |
| [Flow control](flow-control/index.md) | Organize branches, loops, and workflow calls |
| [Code processing](code-processing/index.md) | Process data with SQL or Python |
| [Other nodes](other/index.md) | Process drawings, email, file manifests, and source relationships |

## Select and connect nodes

Each node page describes settings, outputs, and an example. Check that upstream outputs match downstream inputs. See [Variables and data flow](../variables-and-data.md) for variable, state, and output references.

## Common combinations

- **Build a document knowledge base:** Read MOI Volume → General Document Parsing → Segment → Embed and Add to Knowledge Base.
- **Extract fields into a table:** General Document Parsing → Information Extraction → Save to MOI Table.
- **Summarize a recording:** Parse Audio → AI Inference → Save to MOI Volume.

See [Variables and data flow](../variables-and-data.md) for bindings, or choose a [workflow template](../templates/index.md) to start with a predefined flow.

```{toctree}
:hidden:
:maxdepth: 1

AI processing <ai-processing/index>
Data IO <data-io/index>
Flow control <flow-control/index>
Code processing <code-processing/index>
Other nodes <other/index>
```