CSS (Cascading Style Sheets) is a style sheet language that is used in web design to control the presentation and visual styling of web pages. CSS allows web designers to separate the content (HTML) from the presentation, making it easier to maintain and update the website's appearance. Some of the key uses of CSS in web design include:

• Defining the layout, spacing, and positioning of website elements
• Applying styles, such as colors, fonts, and backgrounds, to the website's content
• Creating responsive designs that adapt to different screen sizes and devices
• Implementing visual effects, animations, and transitions
• Enhancing the overall aesthetic and user experience of the website

By using CSS, web designers can create consistent, visually appealing, and user-friendly websites that are easy to maintain and update over time.