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

# Principals

> Understanding user accounts and service accounts.

**Principal** is a collective term for **user accounts** and **service accounts**. Both entities can be uniquely identified, authenticated, and authorized in CDF. Principals are unique within an organization and, therefore, also within a project in the organization. Principals can access data and create and run processes (transformations, Functions) in a CDF project.

* A **user account** is associated with a **person** who wants to interact with CDF. Each user account has a user profile containing a unique user ID.
* A **service account** is associated with an **application** or **process** that interacts with CDF, such as an extractor or Cognite Functions, rather than a person.

## Authentication for this API

Direct requests to the Principals API to `auth.cognite.com`, similar to organizations.

The Principals API accepts only OAuth tokens issued by `https://auth.cognite.com` (such as those issued when logging into Fusion).

You can also obtain a token by initiating a login flow against the authorization server directly. See the "Authorizations" sections for more information.

## User accounts

The Principals API lets you query user accounts in an organization and retrieve profiles.