Realms are a grouping of users with similar features that are governed by the same configuration. Realms are especially useful when you have different groupings for sites within the same account that are not directly related, or to have a test site with test users without affecting productive user grouping.

Each realm has its own login, registration, integrations, forms, segments, and messaging settings. You should be aware that when creating any of these elements in a realm, it will only affect users of that realm and will have no effect on users of another realm.

You can find more information about Realms in our documentation.