The acronym UI stands for User Interface, which refers to the space where interactions between humans and machines occur. UI design focuses on optimizing the layout, visuals, and overall experience to ensure users can navigate and use a product or application efficiently. Effective UI design enhances usability through thoughtful arrangement of elements, such as buttons and menus, while ensuring aesthetic appeal. A well-designed UI plays a critical role in user satisfaction, as it influences how easily users can achieve their goals within a digital environment.