CSS (Cascading Style Sheets) is the language used to style and design web pages, controlling colors, fonts, layouts, and visual effects. With CSS, developers can make websites more attractive and enhance user experience.

CSS works alongside HTML, where HTML defines the structure of the page, while CSS adds styling and aesthetics. It also provides advanced features like Responsive Design, ensuring that websites look great on all devices, from smartphones to large screens.

With the evolution of CSS, new versions and techniques like CSS3 have introduced powerful features such as Transitions, Animations, and Grid & Flexbox Layouts, making web design more flexible and efficient.

Learning CSS is an essential step for any web developer, enabling the creation of visually appealing and highly interactive websites, ultimately improving user engagement and experience.