A cascader helps someone choose an option by moving through levels of related choices. Each choice reveals a smaller set beneath it. It is like choosing a place on a map: first a country, then a region, then a city.
For example, an online store could ask which computer part you need by letting you choose “Computers,” then “Laptops,” then a specific model. This can make a long list easier to explore when the choices naturally belong in groups.
Use a cascader only when each step depends on the choice before it. Show the selected path clearly so people can understand how they arrived at the final option.