Krug's first law of usability
The fundamental premise behind the book's title is straightforward: when a user looks at a web page, it should be self-explanatory and obvious. Every second spent trying to decipher whether an element is clickable, where a button leads, or what an obscure icon means imposes unnecessary cognitive friction. Human beings do not visit a commercial website to solve visual riddles, but to accomplish a practical goal with as little friction as possible.
When a professional visits an online store to download an invoice or buy a piece of office equipment, any visual ambiguity triggers immediate irritation. If a person has to stop their train of thought to wonder where to click to move forward, the interface has failed miserably. Great design is the kind that goes unnoticed, allowing the visitor's attention to stay focused on the task they came to accomplish.
Eliminating mental question marks is the primary duty of anyone who designs digital interfaces. Small accumulated doubts, such as overly clever names for common categories or buttons camouflaged inside body text, wear the user out in a matter of minutes. Making things self-evident at first glance saves precious mental energy and turns a potentially disjointed experience into a natural, welcoming journey.
