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Web Development Lesson 1 of 5

How the Internet & the Modern Browser Work

15:30 Foundations of Modern Web Development

What actually happens when you type a URL in your browser and hit Enter? Understand DNS lookup, TCP/IP handshakes, and DOM tree construction.

Lesson notes

Before writing code, understanding how browsers digest HTML, CSS, and JavaScript empowers you to write significantly faster, bug-free web applications.

What you'll learn

  • The client-server architecture lifecycle
  • The Critical Rendering Path (DOM, CSSOM, Render Tree, Layout, Paint)
  • Why semantic markup accelerates browser rendering performance

1. The 5-Step Request Journey

When you enter a URL: 1) Your browser queries DNS servers to translate the domain into an IP address. 2) A secure TLS/TCP handshake connects your device to the server. 3) The server returns the raw HTML stream. 4) The browser parser constructs the DOM tree. 5) Assets like stylesheets and scripts are requested in parallel.