# Custom User ID integration

Custom User IDs are used to identify your users with your systems such as CRMs, loyalty programs, or authentication systems.

### Create a Custom User ID

1. Go to **Navigator > Settings > Organisation > Compartments**.
2. In the **First-party user account compartments** section, click on **New Compartment**.
3. Specify the following details:

| Parameters | Description                                                         |
| ---------- | ------------------------------------------------------------------- |
| Name       | Name of the Compartment                                             |
| Token      | A technical identifier used to link the Compartment with the JS Tag |

If you have multiple datamarts, don't forget to activate the new Compartment on all other datamarts.