Build Systems
The laws behind the architecture, governing how teams, systems, and estimates really behave.Tesler’s Law
Complexity never disappears; someone absorbs it.
Gall’s Law
Working systems grow from simple ones.
Conway’s Law
Products mirror the teams that build them.
Postel’s Law
Accept input generously, send output carefully.
Goodhart’s Law
Targets stop measuring once they're targets.
Survivorship Bias
The failures you can’t see change the conclusion.
Lindy Effect
What has lasted is likely to last.
Hofstadter’s Law
Everything takes longer than expected.
Pareto Principle
Eighty percent comes from twenty percent.
Zipf’s Law
A few items carry most of the use.
Human-in-the-Loop
Where human judgment sits in automation.
Out-of-the-Loop Problem
Watching automation erodes the skill to take over.
Explainability
Show people why, not just what.
Principle of Least Privilege
Grant only what the task needs.
Apply Standards
The canonical checklists and standards that settle arguments and keep quality from drifting.Nielsen’s 10 Heuristics
Ten usability principles — the standard checklist.
Norman’s Principles
The vocabulary of everyday design.
Rams’ 10 Principles
Ten questions good design must answer.
Shneiderman’s Eight Golden Rules
Eight golden rules of interface design.
Tognazzini’s First Principles
Sixteen principles for interaction design.
WCAG and POUR
Perceivable, operable, understandable, robust.
Curb Cut Effect
Designed for disability, used by everyone.
Chesterton’s Fence
Understand it before you remove it.
Microsoft’s 18 AI Guidelines
Eighteen checks for AI that faces a user.
UI Tenets and Traps
Nine tenets, and the traps that break them.
Design Controls
Targets, feedback, and forgiving controls, tuned to how hands and attention actually behave.Fitts’s Law
Big, close targets are faster.
Steering Law
Narrow paths slow the pointer.
Contour Bias
Rounded feels safe; sharp reads urgent.
Stroop Effect
Conflicting label and color slows people down.
Navigation Patterns
The proven ways users find things.
Cognitive Models of Information Retrieval
Search is a path, not a single query.
Doherty Threshold
Respond within 400 milliseconds.
Change Blindness
Changes go unseen unless attention is on them.
Alarm Fatigue
Too many alerts, and none get through.
Power Law of Practice
Repetition makes every task faster.
Yerkes-Dodson Law
Some pressure helps; too much hurts.
Retain Users
Delight, memory, and habit — the reasons people return long after the first visit.Aesthetic-Usability Effect
Beautiful feels easier to use.
Peak-End Rule
People remember peaks and endings.
Uncanny Valley
Almost-human unsettles more than machines.
Zeigarnik Effect
Unfinished tasks stay on the mind.
Fogg Behavior Model
Behavior needs motivation, ability, a prompt.
Hook Model
Trigger, action, reward, investment — repeat.
IKEA Effect
We overvalue what we help build.
Compose Pages
Where the eye goes and why, and how structure decides what gets seen first.Eye-Scanning Patterns
Six scan shapes from eye-tracking research.
Visual Search
Unique features pop out; similar items slow the hunt.
Banner Blindness
Anything that looks like an ad gets ignored.
Gutenberg Principle
Reading gravity flows toward bottom-right.
Grid and Hierarchy
Grids organize space; hierarchy directs attention.
Golden Ratio
Unequal parts that still relate.
Silver Ratio
A longer, bolder division: 1 to 2.414.
Aspect Ratio
The frame decides what fits and what jumps.
Rule of Thirds
Focal points off center, on purpose.
Rule of Odds
Three or five feel like one group.
Canons of Page Construction
The margins behind readable pages.
Line Length
Keep reading lines between 45 and 75 characters.
Gestalt Principles
How the mind groups what it sees.
Negative Space
The empty space does the organizing.
Von Restorff Effect
The different one gets remembered.
Weber-Fechner Law
Perception scales with ratios, not amounts.
Ebbinghaus Illusion
The same circle looks bigger or smaller in different company.
Müller-Lyer Illusion
Arrow ends change how long a line looks.
Explain Data
Making information effortless to absorb, so understanding costs the reader as little as possible.Data Visualization
Sixteen chart types, grouped by question.
Chartjunk
Ink that shows no data gets in the way.
Universal Icons
The few glyphs everyone already reads.
Picture Superiority Effect
Pictures are remembered better than words.
Processing Fluency
What is easy to process feels true.
Progressive Disclosure
Show essentials now, reveal more later.
Cognitive Load Theory
Working memory is the real bottleneck.
Miller’s Law
About seven chunks, plus or minus two.
Serial Position Effect
First and last stick; middle fades.
Curse of Knowledge
Experts can't imagine not knowing.
Shape Choices
Shaping decisions people can actually make, without the paralysis that too many options bring.Hick’s Law
More choices mean slower decisions.
Jakob’s Law
Your site should work like others.
Principle of Least Astonishment
Behave the way people expect.
Paradox of Choice
Fewer options, easier decisions.
Decision Fatigue
Every choice makes the next one worse.
Satisficing
People pick the first option that is good enough.
Choice Architecture
How options are presented changes what people pick.
Nudge Theory
Make the better choice the easier one.
Default Effect
Most people keep whatever is preselected.
Social Proof
When unsure, people copy what others do.
Anchoring Effect
The first number sets the frame.
Denomination Effect
Small units get spent; big ones get saved.
Ambiguity Effect
Known odds beat unknown ones.
Automation Bias
People over-trust the machine's suggestion.
Dark Patterns
Tricks that win the click and lose the trust.