How Browsers Work

Inside the Browser

Modern browsers transform HTML, CSS, and JavaScript into interactive pages through a complex rendering pipeline.

The Critical Rendering Path

1. DOM Construction: Parse HTML into a tree structure
2. CSSOM Construction: Parse CSS into the CSS Object Model
3. Render Tree: Combine DOM and CSSOM
4. Layout: Calculate positions and sizes
5. Paint: Fill in pixels
6. Composite: Combine layers

JavaScript's Impact

JavaScript is parser-blocking by default. Use async or defer to prevent blocking the render.