# Concepts (deprecated) Overview

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 Concepts are **deprecated** and have been replaced by [Topics](/api/topics/).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

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 They have been replaced by the Topics system, which provides more accurate and comprehensive classification.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](/api/filtering/), [Sorting](/api/sorting/), and [Grouping](/api/grouping/) for syntax.

Fields marked **(deprecated)** are `.search` filters — use the [`search` parameter](/api/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` | ✓ | ✓ | ✓ |