Learn JavaScript comments: single-line, multi-line, and JSDoc documentation with real-world examples. Discover smart commenting strategies and what not to comment for cleaner JS code.

Learn what statements and expressions are in JavaScript, how the interpreter reads your code, and the habits that protect you from silent, hard-to-trace bugs.

Learn three ways to run JavaScript as a complete beginner: the browser developer console, an HTML script tag, and Node.js. And understand exactly what console.log does and why.

Learn how the JavaScript engine works under the hood, what V8 and SpiderMonkey are, how code gets parsed and executed step by step, and what the runtime environment actually is.

Learn how the CSS :is(), :where(), and :has() selectors work, with real examples. Master selector grouping, zero-specificity styling, and the CSS parent selector in one practical guide.

Learn how CSS specificity is calculated using the (A,B,C,D) score system. Understand inline styles, IDs, classes, and elements, and why !important breaks everything.

Learn how CSS pseudo-elements ::before, ::after, ::first-letter,::placeholder, ::selection, and ::marker work, with live visual examples and code you can try right away.

Learn every CSS pseudo-class with visual examples: :hover, :focus, :active, :visited, :checked, :nth-child, :first-child, :last-child, :not(), :is(), and :where() explained clearly.

Learn all seven CSS attribute selectors: target elements by presence, exact value, prefix, suffix, substring, and partial match to style links, inputs, and more without extra classes.

Learn how to group CSS selectors with commas, use descendant and child combinators, and master adjacent and general sibling selectors to write cleaner, more precise stylesheets.