Aggregates versus entities
As discussed, aggregates are conceptually composed of entities and value objects that relate to each other in some way. We need to understand fully what an entity is and the role that it plays in our development process.
Entities and why we need them
Decisions made in DDD are driven by behavior, but behaviors require objects. These objects are referred to as entities. An entity is a representation of data in your system, something that you need to be able to retrieve, track changes on, and store. Entities also typically have an identity key, most commonly an auto-incrementing integer or a GUID value. In code, you would want to create a base entity type that allows you to set the desired key type relative to the derived type. Here is an example of a BaseEntity class in C#:
public abstract class BaseEntity<TId>
{
public TId Id { get; set; }
}
The...
