In order to understand Core Data relationships, it's best to start from the simplest use case of a one-to-one association between two Entities. There are many use cases in the real world that support this type of modeling of objects inside Core Data. In today's lesson, we dive into an example of separating Employee Information into a separate entity, and establishing a one to one relationship with Employee. To further reinforce this concept, let's also create an Address entity that holds onto an employee's address information. Finally, after having finished the creation of these relationships, we go into code to save some dummy information onto our Employee and EmployeeInformation objects.