Breadboarding is how electronic prototypes are made. It focuses on function, has all components and wiring – but no industrial design. Not usable, but it works.
Similar idea is used (by the Basecamp team) to create a product prototype. It has all parts of the interface but doesn't specify the visual design or components.
It's a three-part design:
- Places: Screens, Modals, Menu, etc
- Affordance: Components to which user interacts with
- Connection line: Line that connects one action to its result
Breadboarding focuses on connections, the workflow and hence goes through all functionalities but, doesn't specify anything about the visual behaviour.