What is Microsoft tenant domain?

When purchasing Microsoft products, a new customer shall have Microsoft tenant domain.

In general, Microsoft tenant is the set of services assigned to your organization. Typically, this tenant is associated with one or more of your public DNS domain names and acts as a central and isolated container for different subscriptions and the licenses within them that you assign to user accounts.

For SaaS cloud offerings, the tenant is the regional location that houses the servers providing cloud services. 

Azure PaaS services and virtual machine-based workloads hosted in Azure IaaS can have a tenancy in any Azure data center across the world. You specify the Azure datacenter, known as the location, when you create the Azure PaaS app or service or element of an IaaS workload.

An Azure AD tenant is a specific instance of Azure AD containing accounts and groups. Paid or trial subscriptions of Microsoft 365 or Dynamics 365 include a free Azure AD tenant. This Azure AD tenant does not include other Azure services and is not the same as an Azure trial or paid subscription.

If a new tenant domain is needed, it can be created directly on the platform.

Please be aware of existing MS restrictions for domain creation.