Laws of UX

Psychology-driven constraints for interface decisions, organized by engineering decision. Rules lead; law names follow in parentheses as justification.

Global Principles

These three principles cut across every category below. Apply them everywhere before category-specific rules.

• Remove every element that doesn't serve comprehension. After building, delete one element at a time — if the page still works and communicates clearly, leave it deleted. (Cognitive Load / Occam's Razor)
• Focus engineering on the 20% of features used by 80% of users. The primary flow must be flawless; edge cases adequate. (Pareto / 80-20 Rule)
• Push complexity into the system, not onto the user. Auto-detect timezones, infer file types, pre-fill from context. If the user configures something the system could detect, the system failed. (Tesler's Law)

1. Navigation & Information Architecture

Apply when: designing primary nav, menus, sidebars, site structure, breadcrumbs.