How the Web Works

About this course

The course that explains the machinery underneath every website, including the one you are reading this on. It starts with what actually happens when you open a page: DNS, the connection, the request, the response, and the render. Almost every question about why a site is slow, broken, or behaving oddly turns out to be a question about one of those steps. Then status codes, including the two everyone gets the wrong way round and the redirect distinction that quietly costs sites their search ranking. The middle covers HTML that carries meaning rather than only appearance, and the two things about CSS that confuse everybody: the box model and the cascade. Then the DOM, events, and fetching data, including why fetch does not throw on a 404 and the three states every request has. It ends with why pages feel slow, what accessibility actually requires, and how search engines see a page, including the redirect trap that stops correct pages being indexed at all.

What you will learn

• Trace what happens between typing an address and seeing a page
• Read status codes, and use 401, 403, 301 and 302 correctly
• Write HTML that carries meaning, and explain why it matters for real users
• Explain the box model, margin collapse, and how the cascade resolves conflicts
• Read and change the DOM safely, and handle all three states of a request
• Diagnose why a page feels slow, and why a correct page might not be indexed

Before you begin

• No experience needed
• Some familiarity with JavaScript helps for the DOM section, but is not required
• A browser with developer tools, which every browser has