In 2020, CSS frameworks play a crucial role in web design by offering tools that enhance efficiency, user experience, and browser compatibility. Among the popular frameworks, Bootstrap, developed by Twitter, is widely favored due to its comprehensive documentation and ease of use, making it ideal for rapid development and consistent design across browsers. Foundation provides advanced customization options and flexibility, while Materialize, created by Google, emphasizes design aesthetics and responsiveness. Other notable frameworks include Semantic UI, known for its intuitive usage and variety of themes, and Bulma, which leverages Flexbox for innovative design. Tailwind stands out for its utility-first approach that prioritizes speed and customization, whereas Ant Design is favored for its polished look and comprehensive component library. Frameworks like Tachyons and Primer, although less popular, offer unique advantages in terms of modularity and systematic design, respectively. Ultimately, the choice of a CSS framework depends on project requirements and the need for cross-browser testing to ensure compatibility.