Browser Fundamentals
The browser is a runtime, not a document viewer: networking, parsers, a JavaScript engine, a layout engine, a paint system, a compositor, storage and a security sandbox, split across processes that fail independently.
Not a document viewer with scripting bolted on: a sandboxed application platform with a scheduler, a memory model, a renderer and a security boundary.
URL to pixels: resolution, connection, request, streaming HTML, DOM and CSSOM, style, layout, paint, composite — and what blocks what.
Browser, renderer, network, GPU and utility processes — why a page can hang without taking the browser with it, and what that means for your code.
Intent, event, state, logic, DOM, network, layout, paint, pixels, feedback — the chain every lesson in this domain is a zoom into.
Scheme, host and port together form the unit of trust — and nearly every confusing browser restriction is that boundary being enforced.
The boundary that keeps this domain honest: the browser-executed application and the interaction a person feels — and where everything else properly lives.