What's an Aggregate Root?

Question

I\'m trying to get my head around how to properly use the repository pattern. The central concept of an Aggregate Root keeps coming up. When searching both the web and Stack

Answer 1

In the context of the repository pattern, aggregate roots are the only objects your client code loads from the repository.

The repository encapsulates access to child objects - from a caller's perspective it automatically loads them, either at the same time the root is loaded or when they're actually needed (as with lazy loading).

For example, you might have an Order object which encapsulates operations on multiple LineItem objects. Your client code would never load the LineItem objects directly, just the Order that contains them, which would be the aggregate root for that part of your domain.