A dropdown list is a user interface element that allows users to select one option from a list of choices. When a user clicks on the dropdown, it expands to reveal the available options, which can include text, numbers, or other items. This feature is commonly used in forms and applications to streamline the selection process and save space on the screen. Dropdown lists are often implemented in programming languages and frameworks, such as HTML and JavaScript. They enhance user experience by providing a clear and organized way to present multiple options without overwhelming the user with too much information at once.