Eye-Scanning Patterns
Six reading behaviors documented across decades of eye-tracking research — F, Z, Marking, Spotted, Layer-Cake, and Bypassing.
Gutenberg Principle
The four-quadrant model of reading gravity — Primary, Strong Fallow, Weak Fallow, Terminal — and why CTAs belong in the bottom-right.
Data Visualization
Sixteen chart types grouped by the question they answer — comparison, relationship, distribution, and composition.
Gestalt Principles
How the mind automatically groups what it sees — proximity, similarity, closure, common region, and the other rules of perception that shape every layout.
Grid & Hierarchy
The invisible scaffolding underneath every well-resolved interface — 12-col grids, baseline rhythm, golden ratio, and the techniques that direct attention.
Navigation Patterns
The layers that help people know where they are and where they can go — global, local, utility, breadcrumbs, and footer nav, plus how AI is reshaping them.
Universal Icons
The small set of glyphs the whole world already reads — menu, search, settings, cart — plus the principles for using them well and the new AI sparkle.
Nielsen's 10 Heuristics
Jakob Nielsen's classic usability principles — visibility of system status, match between system and real world, error prevention — with modern examples for each.
Norman's Principles
Affordances, signifiers, mapping, feedback, constraints — Don Norman's principles from "The Design of Everyday Things" and how they re-emerge in conversational UI.
Rams' 10 Principles
Dieter Rams wrote these in the 1970s while running design at Braun. Fifty years later they still describe what makes a digital product genuinely good.
Tognazzini's First Principles
Bruce "Tog" Tognazzini's sixteen rules for interaction design — anticipation, autonomy, latency, protect the user's work — refined across decades at Apple, Sun, and NN/g.
WCAG & POUR
The four principles of accessibility — Perceivable, Operable, Understandable, Robust — plus the key success criteria every product team should know.
Conway's Law
Any organization that designs a system produces a design that copies the org chart. Predicting product seams from team shape — and the inverse Conway maneuver.
Fitts's Law
Big and close. Paul Fitts's 1954 law governs every button, link, and tappable region — and why edges, corners, and the Mac menu bar feel so fast.
Fogg Behavior Model
B = MAP. A behavior happens when Motivation, Ability, and a Prompt converge — the model behind behavior design, persuasive tech, and Tiny Habits.
Gall's Law
Complex systems that work evolved from simple systems that worked. John Gall's 1975 rule for why the grand from-scratch design rarely ships.
Goodhart's Law
When a measure becomes a target, it ceases to be a good measure. The rule behind every gamed KPI — and a warning about training metrics.
Hick's Law
More choices = longer decisions. The 1952 law that governs every menu, every settings panel, and every product page — and the techniques that work around it.
Hofstadter's Law
It always takes longer than you expect, even when you account for this law. The self-referential rule behind every missed estimate and every 99% progress bar.
Hook Model
Nir Eyal's four-step loop — Trigger, Action, Variable Reward, Investment — behind every habit-forming product, plus where it tips into manipulation.
Jakob's Law
Users spend most of their time on other sites, so they expect yours to work the same way — and a look at how AI is rewriting those conventions.
Miller's Law
About seven things, plus or minus two. Miller's 1956 study put a number on working memory — and chunking, the trick around it that quietly shapes every well-designed interface.
Paradox of Choice
When more options means fewer decisions. Schwartz's Paradox of Choice, Iyengar's jam study, and the techniques for getting users past decision paralysis.
Pareto Principle
The 80/20 rule. Most of the effect comes from a small fraction of the causes — in users, in features, in support tickets, in code. Knowing which 20% is the whole game.
Postel's Law
"Be conservative in what you send, liberal in what you accept." The robustness principle from RFC 760 — and the rule behind every forgiving form field on the web.
Power Law of Practice
Time to perform a task drops as a power of repetitions. Snoddy 1926 / Newell & Rosenbloom 1981 — and the curve onboarding, shortcuts, and AI all shift.
Tesler's Law
The Law of Conservation of Complexity — every system has an irreducible complexity that can only be moved between the user and the system, never removed.
Weber-Fechner Law
The smallest noticeable change scales with the original. Weber 1834 / Fechner 1860 — the law behind type scales, contrast ratios, pricing, and notification fatigue.
Yerkes-Dodson Law
Performance rises with arousal — to a point — then falls. The 1908 inverted-U curve behind flow, overwhelm, and why calm UI is right for complex tasks.