A collapsible menu is a user interface element that allows users to expand or collapse a list of options. This feature helps save space on a webpage or application by hiding less frequently used items until they are needed. When a user clicks on a menu title, the related options are revealed, making navigation more efficient. These menus are commonly used in websites and mobile apps to organize content, such as categories or settings. By using a collapsible menu, designers can create a cleaner layout, improving user experience while ensuring that important information remains easily accessible when required.