CSS, or Cascading Style Sheets, is a language used to style the appearance of web pages written in HTML and XHTML. It allows web developers to control the layout, typography, colors, and other visual aspects of a webpage, ensuring consistency and enhancing user experience.
CSS works by applying styles to HTML elements using selectors, properties, and values. Selectors target specific elements or groups of elements, while properties define the style attributes to be applied, such as font size, background color, or margin size. Values specify the desired characteristics for each property, such as numerical values, color codes, or predefined keywords.
By separating content from presentation, CSS enables efficient design management and facilitates website maintenance and updates. It promotes modularization, reusability, and responsiveness, allowing web pages to adapt to different devices and screen sizes effectively.