Time was, design was something of a blueprint. You drafted up the poster or magazine or brochure. You knew the materials that would go into it. You knew the printer's color process. You knew the paper stock you'd be using. You knew the tolerances of the machinery involved. And you could design for it, accommodate and adapt to the limitations and contingencies, design for the essential result. This font in this point size in this color positioned right here on this stock cropped just so. There were, of course, unknowns, because offset printing can go a bit wild when the machines start spinning, but with experience you could learn to work with those unknowns, because in the end you knew, in the end, what you were making would be consistent. A magazine was a magazine. A business card was a business card.
But in the digital world, the requirements are different. Interaction design — good design, functional design, usable design, design you can use — is alive. It moves. It reacts. It responds. It lives. You can see it, click on it, touch it. In apps — web apps, iPhone apps, Android apps, desktop apps — design can't remain static. It lives in the interactions. The affordances. The feedback. The forgiveness. The familiar patterns. Design in the digital world can't be contained in Photoshop or AutoCAD or Quark.
Design isn't a matter of creating a blueprint. It's more like engineering DNA. Design lives!
Design lives in code
If the code doesn't work, there is no design. It's not there. Not alive.
Without code, the design can't happen. And while we can doodle out design ideas on napkins, in wireframes, in Photoshop or InDesign files, we can't realize actual designs except in code. The design lives in the code.
The code, it's alive!
Design lives in the device
Desktop screen or phone screen? Click it or touch it? Lean forward or lean back? Whether you design for it or not, the device upon which your design is experienced is part of your design. Whatever your intentions, the user's experience of your web app in Safari on an iMac is going to be very different from the UX on an iPad.
Touch screen action is different from mousing action: There is no
a:hover in touchscreens (currently). Nobody will see it. Small buttons and links may be clickable with a razor sharp mouse pointer, but they're not clickable when taking pudgy fingers to the touchscreen.
Device becomes context. Device is an integral part of the experience. You can't experience the design without the device.
Marshall McLuhan said, "The medium is the message." The medium defines the experience. The experience defines the medium. You can't separate the newscast from the television that brings it into your livingroom. Both affect our experience. (Right here I'll stop paraphrasing McLuhan, which is impossible to do in a paragraph, hoping my point is made.)
The device is part of the user's experience of the design. Your design is fundamentally different when experienced via different devices. Your 'desktop' layout provides fundamentally different experiences when viewed on a computer screen vs. a touch-screen tablet.
And bear in mind: We're not done being presented with new devices. We're close to having heads-up "browsers" in eyeglasses. Not far off: wall screens. What about handheld devices that fold like paper? Holographic projections that read your gestures?
Just think of all the lives your design will live in the devices of the future!
Design lives in the user
If a design happens, and nobody is around to experience it....
An unusable design doesn't live. A confusing design doesn't live. The design that drives user away out of frustration, confusion, annoyance, obnoxiousness, over-complexity, absence of affordances, etc. lies dead in its own bytes.
Without the user, of what use is the design?
The user experience is the validation, the completion of the design. Through the user's experience, the design comes alive.
And the interesting thing: the actual user experience often has little to do with the intention of the actual designer. You think people will love Feature X, but everyone is clicking on Feature Y. Which has the "better" design? You can't use intentions, just the design that lives for the users, lives on the device, lives on the screen, lives in the code.
And when you consider the multiple users, each with her own story, and multiple devices, each with its own dimensions, affordances, constraints, a single design lives in an untold number of user experiences.