# Obtain entity identifiers (Entity GUID)
source: https://developer.mastercard.com/business-payment-controls/documentation/use-cases/00-entity-identifier/index.md

This API supports the following use cases for obtaining entity identifiers:

## Obtain entity identifiers {#obtain-entity-identifiers}

* [Obtain your entity identifier](https://developer.mastercard.com/business-payment-controls/documentation/use-cases/00-entity-identifier/index.md#obtain-my-entity-identifier)
* [Obtain descendent entity identifiers](https://developer.mastercard.com/business-payment-controls/documentation/use-cases/00-entity-identifier/index.md#obtain-descendent-entity-identifiers)

## Obtain my entity identifier {#obtain-my-entity-identifier}

In order to [register a Real Card](https://developer.mastercard.com/business-payment-controls/documentation/use-cases/01-real-cards/#register-a-real-card-with-controls) and conduct any further operations, an entity identifier, also known as an ownerGUID or entityGUID is required. You can obtain the identifier for your organization using the Entities API.
Diagram 00-get-your-id
API Reference: `GET /entities/user-entity`

## Obtain descendent entity identifiers {#obtain-descendent-entity-identifiers}

If your entity has any descendent entities registered, you can obtain their identifying entity GUIDs using the endpoint below. It is important that [Real Card registration](https://developer.mastercard.com/business-payment-controls/documentation/use-cases/01-real-cards/#register-a-real-card-with-controls) is associated with the correct entity in the hierarchy.
Diagram 00-get-descendant-id
API Reference: `GET /entities/{guid}/descendants`