Python list items can be lists. As a result, we get nested lists, or lists of lists. Let's look at an example of a nested list:

numbers = [1, [1, 2, 3], 2, [3, 4, 5, [7, 9]]]

What is a list?\nA list is a collection that is ordered and changeable. Moreover, this collection allows duplicate elements.

What is a dictionary?\nA dictionary is an ordered and changeable collection with no duplicate members.\n\nA dictionary holds `key:value` pairs. \n\nKey-value is provided in the dictionary to make it more optimized. 

What is a tuple?\nA tuple is a collection that is ordered and unchangeable. This collection allows duplicate elements.\nA tuple is a collection that is very similar to a list. The sequence of values stored in a tuple can be of any type, and they are indexed by integers. Values of a tuple are syntactically separated by ‘commas’. Although it is not necessary, it is more common to define a tuple by closing the sequence of values in parentheses. This helps to understand the Python tuples more easily.

What is a set?\nIn Python, a `set` is an `unordered collection` of data type that is `iterable`, `mutable` and has `no duplicate elements`. The order of elements in a set is undefined, though it may consist of various elements.\n\nThe major advantage of using a set as opposed to a list is that it has a highly optimized method for checking whether a specific element is contained in the set.