> ## 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.

# Fields Overview

> Schema reference for Fields entities

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](/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 |
| -------------------------------------- | :--: | :-------: | :----: |
| `cited_by_count`                       |   ✓  |     ✓     |    ✓   |
| `default.search` **(deprecated)**      |      |           |    ✓   |
| `display_name`                         |   ✓  |           |    ✓   |
| `display_name.search` **(deprecated)** |      |           |    ✓   |
| `domain.id`                            |   ✓  |     ✓     |    ✓   |
| `from_created_date`                    |   ✓  |           |    ✓   |
| `id`                                   |   ✓  |     ✓     |    ✓   |
| `subfields.id`                         |   ✓  |     ✓     |    ✓   |
| `works_count`                          |   ✓  |     ✓     |    ✓   |