Mockup
A mockup is a visual representation of a proposal that shows how it will look before it is produced or developed
What it means, how it is used and where it comes up, with its related concepts.
What it is and how it works
It makes it possible to review layout, identity and hierarchy in a specific context. It may be static and not show how the interaction works. To validate behaviour or task comprehension, a prototype that allows people to go through the experience is usually needed.