Glossary term
What is CSSOM (CSS Object Model)?
CSSOM stands for CSS Object Model.
The browser's tree of styles. The browser waits for it before it paints, so CSS can block the first paint.
Learn it properly · The Browser ContractLesson 0: What Happens When You Type a URL (The Full Version)The full trip from pressing Enter to seeing pixels: DNS, TCP, TLS, HTTP, then reading the page and painting it. Caches skip most steps. Every other lesson in this series fits on this map.