The very first drawings made of a given character, costume, environment, set or vehicle that must be built, drawn or modeled in a production. These come before any plan, Model Sheet, Storyboard, or other technical drawing. Usually go through a lot of revisions. Seeing them in sequence allows a viewer to see the evolution of a character or prop design. A favorite unlockable bonus feature for video games and home video releases. Designs of this kind may also be found collected in a work's artbook, or sometimes photobook, where they may also show alternatives that might of been cut from the finished work.
Should also not be confused with conceptual art, which is a kind of art where the idea behind a work takes precedence over its material qualities.