What is CSS?

CSS (Cascading Style Sheets) is the language that controls how HTML looks. HTML says what something is; CSS says how it should look and where it should go.

Without CSS, every website would be black text on a white background in one long column. With CSS you control colours, fonts, spacing, layout, animations and how the page adapts to phones.

Before and after

<h1>Welcome to TechSnow</h1>

h1 {
  color: #1c6fa8;
  font-family: Arial, sans-serif;
  font-size: 48px;
  text-align: center;
}

The same <h1> is now blue, large, centred and in a different font, without changing the HTML at all.

What does "cascading" mean?

Many CSS rules can apply to the same element. The cascade is the set of rules the browser uses to decide which one wins. You will learn exactly how in the Cascade and Specificity lesson.