John Gruber
The Gap Theory of UI Design
“Consistency” is widely held as a precept of good UI design. But what traditionalists often mean when they speak of UI consistency is really about uniformity. But UI design today — whether it be for desktop, mobile, or web apps — is often about expressing individuality, and thus in opposition to uniformity. Today, UIs are aspects of branding; we create distinctive personalities for software. Let's figure out which aspects of consistency remain essential, useful, and relevant today.