Nested lists in Python are essentially lists within lists. They are a powerful feature that allows you to create complex data structures with ease. A nested list is just like a regular list, but the elements within it can be lists themselves, which can further contain lists, and so on, creating a hierarchy of lists.

Creating and Accessing Nested Lists

To create a nested list, you simply define a list with other lists as its elements. Here's an example of how you might create a nested list:

In this nested list, the second element is a list containing two strings, 'bb' and 'cc'. To access elements within a nested list, you use multiple indices. For example, nested_list[1][0] would give you 'bb', as it refers to the first element of the second list.

Modifying Nested Lists

You can modify elements in a nested list by accessing them using their indices and assigning new values. For instance: