> For the complete documentation index, see [llms.txt](https://developer.abacum.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.abacum.ai/essentials/concepts.md).

# Concepts

The rules that apply to every endpoint.

These pages explain the rules that apply to every endpoint. Read them before you build an integration.

| Page                                                                     | What it covers                                                    |
| ------------------------------------------------------------------------ | ----------------------------------------------------------------- |
| [Access and permissions](/essentials/concepts/access-and-permissions.md) | Which endpoints each user role can call                           |
| [Rate limits](/essentials/concepts/rate-limits.md)                       | How many requests you can send                                    |
| [Errors](/essentials/concepts/errors.md)                                 | Each status code, and what to do about it                         |
| [Download links](/essentials/concepts/download-links.md)                 | How the data endpoints return files, and how long each link lasts |
| [Filter by period](/essentials/concepts/filter-by-period.md)             | How to limit data to a date range                                 |
| [Data file format](/essentials/concepts/data-file-format.md)             | The columns in each file, and the metadata                        |
| [Pagination](/essentials/concepts/pagination.md)                         | How to page through the endpoints that return lists               |

## The Import API

The Import API loads data into an Abacum dataset. It has one endpoint: `POST /public-api/load-data`. Before you call it, check two things:

* The Import API is enabled for your organization. This is a separate organization setting.
* The target dataset exists in Abacum, and it uses an Import API connection.

See [Set up the Import API](/guides/import-api-guides/set-up-the-import-api.md), then [Load data](/guides/import-api-guides/load-data.md).