> ## Documentation Index
> Fetch the complete documentation index at: https://hexagraph-docs.voyla.in/llms.txt
> Use this file to discover all available pages before exploring further.

# Subfields API — Overview

> Overview of Hexagraph's registry of specialized research subfield disciplines.

Subfields represent specialized research disciplines within a field of study. They sit below fields in the Hexagraph research hierarchy and group together closely related research topics.

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## Filter and Sort Fields

The API supports filtering, sorting, and grouping operations on these fields:

| Field            | Sort | Filter |
| ---------------- | :--: | :----: |
| `id`             |   ✓  |    ✓   |
| `name`           |   ✓  |        |
| `outputs_count`  |   ✓  |    ✓   |
| `cited_by_count` |   ✓  |    ✓   |
| `field.id`       |   ✓  |    ✓   |
| `domain.id`      |   ✓  |    ✓   |
| `topics.id`      |   ✓  |    ✓   |

***

## Available REST Endpoints

* **[Get a single subfield](/api-reference/subfields/get-single-subfield)**: `GET /subfields/{id}` — Fetch details for a single subfield.
* **[List subfields](/api-reference/subfields/list-subfields)**: `GET /subfields` — Retrieve all specialized research subfields.