# Fields Overview

Fields are the second level of the OpenAlex topic hierarchy. There are 26 fields spread across 4 domains. Each field contains multiple subfields.

The topic hierarchy is: Domain → **Field** → Subfield → Topic

## All 26 fields

| ID | Name | Domain |
|---:|------|--------|
| 11 | Agricultural and Biological Sciences | Life Sciences |
| 12 | Arts and Humanities | Social Sciences |
| 13 | Biochemistry, Genetics and Molecular Biology | Life Sciences |
| 14 | Business, Management and Accounting | Social Sciences |
| 15 | Chemical Engineering | Physical Sciences |
| 16 | Chemistry | Physical Sciences |
| 17 | Computer Science | Physical Sciences |
| 18 | Decision Sciences | Social Sciences |
| 19 | Earth and Planetary Sciences | Physical Sciences |
| 20 | Economics, Econometrics and Finance | Social Sciences |
| 21 | Energy | Physical Sciences |
| 22 | Engineering | Physical Sciences |
| 23 | Environmental Science | Physical Sciences |
| 24 | Immunology and Microbiology | Life Sciences |
| 25 | Materials Science | Physical Sciences |
| 26 | Mathematics | Physical Sciences |
| 27 | Medicine | Health Sciences |
| 28 | Neuroscience | Life Sciences |
| 29 | Nursing | Health Sciences |
| 30 | Pharmacology, Toxicology and Pharmaceutics | Life Sciences |
| 31 | Physics and Astronomy | Physical Sciences |
| 32 | Psychology | Social Sciences |
| 33 | Social Sciences | Social Sciences |
| 34 | Veterinary | Health Sciences |
| 35 | Dentistry | Health Sciences |
| 36 | Health Professions | Health Sciences |

## Filter, sort, and group_by fields

The API supports filtering, sorting, and grouping on fields 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 |
|-------|:----:|:--------:|:------:|
| `cited_by_count` | ✓ | ✓ | ✓ |
| `default.search` **(deprecated)** |  |  | ✓ |
| `display_name` | ✓ |  | ✓ |
| `display_name.search` **(deprecated)** |  |  | ✓ |
| `domain.id` | ✓ | ✓ | ✓ |
| `from_created_date` | ✓ |  | ✓ |
| `id` | ✓ | ✓ | ✓ |
| `subfields.id` | ✓ | ✓ | ✓ |
| `works_count` | ✓ | ✓ | ✓ |