Why is Identifiable necessary when creating @Obserable for SwiftUI

Hello, I'm new to SwiftUI and I've been enjoy using @Obserable pair with my View. Question, I saw a lot of the example online also have the @Obserable conforms to Identifiable. Why is that necessary?

It's interesting that I don't even need to provide the id for Identifiable. How does this work internally with SwiftUI?