This post is intended to provide a high-level description of the Common Data Service. It took me some effort to come up with what I feel is a good summarized description, but, I eventually settled on this:
The Common Data Service is a scalable and standardized data store for integrating between and with Dynamics 365 applications.
Some of the advantages of the Common Data Service are below.
Standardized entities/fields between applications (Common Data Model)
The common data model provides a standardized set of entities/fields. The schema for these entities is automatically added when a database is created, and they cannot be deleted. Custom entities/fields can also be added as necessary. However, it is best to use the standardized entities/fields when possible. Using the standard model ensures that new features or apps can be leveraged by your application. Standardizing the model also allows developers that are familiar with the Common Data Service structure to quickly become familiar with other applications that utilize the same structure.
Bringing data together in a single database helps to eliminate data silos between applications. It also allows data to be reported on from a central location. My initial thought was that the Common Data Service could potentially be used as a data warehouse. However, with the current limit of 10GB per database, I do not think this is a good fit nor is it Microsoft’s intention for the service.
Data Integration Service
This service provides a standard set of maps for integrating data with the Common Data Service. Two examples of these are Dynamics 365 for Sales and Dynamics AX. This is a core component of the Prospect to cash solution.