List is an ordered collection of elements by index. Key methods of List are : get(int index), indexOf(Object o), add(int index, Object o), etc. A Set cares about Uniqueness, it doesn\'t allow duplicates elements. The equals() method helps you to find out whether two objects are identical. A map stores the elements in the form of Key/Value pairs. Here key and value both are objects. A map cares about unique key (unique ID) to a specific value. You can search value in a Map by giving its key.