You create a realm to provide a management space where you can create users and give them permissions to use applications. At first login, you are typically in the _master_ realm, the top-level realm from which you create other realms.
When deciding what realms you need, consider the kind of isolation you want to have for your users and applications. For example, you might create a realm for the employees of your company and a separate realm for your customers.
Your employees would log into the employee realm and only be able to visit internal company applications. Customers would log into the customer
realm and only be able to interact with customer-facing apps.
The current realm is now set to the realm you just created. You can switch between managing different realms by pointing to the top left corner to click *Select Realm*.
* Alternatively you can import a JSON document that defines your new realm. For more detail, see the xref:assembly-exporting-importing_{context}[Export and Import] chapter.