CSS is a style sheet language used to style and format web pages. Without it, most websites would be pretty dull — mainly consisting of black text on a white background. CSS is a pillar of modern web development, and its rules and syntax are pretty straightforward, so you can pick up on it quickly.

CSS allows you to customize the format, layout, and color of HTML web pages and keeps websites responsive and consistent across different devices. With its advanced features, you can animate web pages without using JavaScript.

There's some debate over whether CSS is a "real" coding language since it lacks traditional programming logic. Some draw a line between coding languages used to tell a computer how to execute a task and markup and style languages used for structure and presentation. But at the end of the day, you're using code to communicate with technology.