What is a business invariant? What is an invariant? Does it have a nice Dutch analog? Source(s): https://www.codegenes.net/blog/what-is-the-difference-between-invariants-and-validation-rules/#what-are-invariants-in-ddd https://lostechies.com/jimmybogard/2009/02/15/validation-in-a-ddd-world/