The purpose of a UI framework in web development is to provide a structured set of tools and components for building graphical user interfaces. These frameworks enable developers to create consistent, efficient, and responsive layouts and interactions while streamlining the development process. By offering predefined elements such as buttons, forms, and navigation components, UI frameworks reduce the need for repetitive coding, allowing developers to focus on functionality and user experience. Additionally, many frameworks include responsive design features, ensuring that applications run smoothly across various devices and screen sizes, ultimately improving overall user satisfaction.