A cascading dropdown, also known as dependent or linked dropdown, is a user interface element commonly used in forms. It consists of two or more dropdown lists where the options in one dropdown are dynamically updated based on the selection made in another dropdown. The goal is to provide a more interactive and user-friendly experience by narrowing down the available options based on user choices.
Let's say you have two dropdown lists: one for selecting a Person and another for selecting a Group. The options in the group's dropdown would depend on the person selected. As the user chooses a person, the group dropdown is dynamically updated to show only the groups associated with the selected person.
Cascading dropdowns are commonly used in various scenarios, such as address forms, product categorization, and any situation where the available options depend on a prior selection.