Microsoft Dataverse

The Common Data Service (CDS) it is a service for storing data in the could. It is the back-end to Model-Driven Apps and by that also to some of the Dynamics apps e.g. Dynamics Sales and Dynamics Customer Service (former CRM-parts in Microsoft Dynamics CRM). The Common Data Service is more than just storage in the cloud. It also comes with concepts like security (configure security models for your apps), business logic and data integration.

Microsoft Resources

Microsoft Docs: https://docs.microsoft.com/en-us/powerapps/maker/common-data-service/data-platform-intro