Two sides of a coin The key to concept design is, perhaps not surprisingly, the idea of concepts. A concept is two things at once. On the one hand, a “concept” means you’d expect it to mean: a mental construct that you need to understand to be able to use an app effectively. So you might that to use Photoshop you need to understand the “concept of a layer”; to use Facebook you need to understand the “concept of friending”; and so on.
