What Is CSS?

Cascading Style Sheets (CSS) tell the browser how to display the text and other content that you write in HTML.

Note that CSS is case-sensitive so be careful with your capitalization.

CSS has been adopted by all major browsers and allows you to control:

There are three main ways to apply CSS styling.

  1. apply inline styles directly to HTML elements with the style attribute
  2. place CSS rules within style tags in an HTML document
  3. write CSS rules in an external style sheet, then reference that file in the HTML document

Even though the first two options have their use cases, most developers prefer external style sheets because they keep the styles separate from the HTML elements. This improves the readability and reusability of your code.

The idea behind CSS is that you can use a selector to target an HTML element in the DOM (Document Object Model) and then apply a variety of attributes to that element to change the way it is displayed on the page.