Modularity
“Write simple parts connected by clean interfaces.”
This rule from Eric Raymond’s book The Art of Unix Programming, while referring to software architecture, can also be applied to the structure of a user interface. The point is to build small chunks of code that can be tested and upgraded separately, reducing the complexity of the whole. The correlation in UI design is to create bounded, easily understood interactions that become robust through integration. There are several benefits to doing this.
For one, each piece—each widget, if you will—can be individually refined. Every piece of software using a widget can then benefit when that widget is improved. It becomes easier to create a design pattern library or UI style and behavior guide, which allows developers to reuse code and shortens the process of mocking up new UIs. The challenge comes in weaving the pieces together into a seamless visual and behavioral experience. You don’t want to end up with a Frankenstein UI, in which everything looks and feels as if it were cobbled together and bolted on.
