is a micro-book about interfaces over the ages: from cave paintings to Google Glass to your latest note-taking app. It’s important to understand why we build interfaces in order to get better at building them. The purpose of any interface, regardless of the technology, is to retrieve, decode, modify, and/or distribute information. The core purpose of graphics in a GUI is not to be pretty The purpose is to be informative. Some questions to ask yourself when you’re designing an interface: Number five is a bit too bold for my taste, but the first four are valuable guidelines.