Introducing Interaction-Driven Design

TL;DR: IDD is an iterative approach to software design and development based on Outside-In Development which focuses on modeling behavior according to the external usage of the system while maintaining an internal representation of cohesive business components.
Before reading this post, I strongly recommend you read the two previous blog posts that serve as a foundation to this blog: MVC, Delivery Mechanism and Domain Model and A Case for Outside-In Development.