CSS, or Cascading Style Sheets, defines the look and formatting of that HTML. Both are essential to coding your own website, and here's how to get acquainted with them.

Make sure you validate your HTML and CSS, using a service like the W3C’s validator. This will warn you about obsolete tags and other errors that may make your HTML less robust.

We’ll use three essential tools: HTML, CSS, and JavaScript (see graphic). ... Use tags like headers to create bold titles for each section. Then, add text to tell your story.