Are data types of containers mutable or immutable in their structure?

In Python, container data types are divided into mutable and immutable.

• Mutable containers (for example, lists list, sets set, dictionaries dict) allow modifying their contents after creation: adding, removing, or changing elements.

• Immutable containers (for example, tuples tuple, strings str) have a fixed structure and content after creation — any operations that seem to modify them actually create a new object.

Example of a mutable container:

lst = [1, 2, 3]
lst.append(4)  # the list has changed

Example of an immutable container:

t = (1, 2, 3)
# t[0] = 10  # will cause an error, tuples cannot be changed

Thus, the structure of mutable containers is modifiable, while immutable ones are fixed.