As application complexity increases, a desirable attribute of an IT system is that it can be broken into smaller, loosely coupled components. This means that IT systems should be designed in a way that reduces interdependencies—a change or a failure in one component should not cascade to other components.
A way to reduce interdependencies in a system is to allow the various components to interact with each other only through specific, technology-agnostic interfaces (e.g., RESTful APIs). In that way, technical implementation detail is hidden so that teams can modify the underlying implementation without affecting other components. As long as those interfaces maintain backwards compatibility, deployments of difference components are decoupled.