> ## Documentation Index
> Fetch the complete documentation index at: https://developers.openalex.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Concepts (deprecated) Overview

> Schema reference for Concepts (deprecated) entities

<Warning>
  Concepts are **deprecated** and have been replaced by [Topics](/api-reference/topics). The concepts endpoints remain functional but will not receive updates.
</Warning>

Concepts were a hierarchical taxonomy of research areas derived from Wikidata. They have been replaced by the Topics system, which provides more accurate and comprehensive classification.

## Filter, sort, and group\_by fields

The API supports filtering, sorting, and grouping on concepts fields. See [Filtering](/guides/filtering), [Sorting](/guides/sort), and [Grouping](/guides/grouping) for syntax.

Fields marked **(deprecated)** are `.search` filters — use the [`search` parameter](/guides/searching) instead.

| Field                                  | Sort | Group\_by | Filter |
| -------------------------------------- | :--: | :-------: | :----: |
| `ancestors.id`                         |   ✓  |     ✓     |    ✓   |
| `cited_by_count`                       |   ✓  |     ✓     |    ✓   |
| `default.search` **(deprecated)**      |      |           |    ✓   |
| `display_name`                         |   ✓  |           |    ✓   |
| `display_name.search` **(deprecated)** |      |           |    ✓   |
| `from_created_date`                    |   ✓  |           |    ✓   |
| `has_wikidata`                         |   ✓  |     ✓     |    ✓   |
| `ids.openalex`                         |   ✓  |     ✓     |    ✓   |
| `level`                                |   ✓  |     ✓     |    ✓   |
| `openalex`                             |   ✓  |     ✓     |    ✓   |
| `openalex_id`                          |      |     ✓     |    ✓   |
| `summary_stats.2yr_mean_citedness`     |      |     ✓     |    ✓   |
| `summary_stats.h_index`                |      |     ✓     |    ✓   |
| `summary_stats.i10_index`              |      |     ✓     |    ✓   |
| `wikidata_id`                          |      |     ✓     |    ✓   |
| `works_count`                          |   ✓  |     ✓     |    ✓   |