How to read this book

The chapters run in an order, and the order is an argument: start with how interactions should respond, then how motion should be used, then how the pieces are built, then how the whole is made and judged. But every section stands on its own, and the glossary and people appendix let you enter anywhere. The glossary defines each term of art in the words of the person who coined or best explained it. The people appendix says who the authors are and points at their sites, which are primary sources in a way a summary can never be. The reading list collects every essay, library, site, and hub the chapters cite.

Figures are the point. Each one is built so that operating it does the thing the surrounding section teaches: you set a spring’s stiffness and watch it overshoot, you swipe a card and see when the action commits, you stack toasts and discover why keyframes fail. Every figure states where its numbers come from. “Constants from the source” means the defaults are the ones the cited essay or library documents; “illustrative numbers” means the ranges are hypothetical inputs for you to explore, and no claim rests on them. The one below is the smallest complete example of the pattern.

Nothing in a figure shifts the page. Every state stays mounted, and the tallest one sets the height, so you can play without losing your place. Animations respect your reduced motion preference. Controls work from the keyboard. These are the same rules the authors in this book hold themselves to, and it would be strange to write about them in a site that broke them.

A word on quotation. Chapter prose is original. Short quotes appear where an author’s wording is the point, always attributed, and the glossary quotes verbatim by design. The sources are better than any summary of them; if a section makes you want to read the essay it draws on, that is the intended effect. Start with the first gesture you were ever taught.