What is the purpose of using immutable data types in Python and what role do they play?

Immutable data types in Python (such as strings, tuples, numbers) are used to ensure safety and predictability of the code. Their roles:

• Guarantee that the value of an object does not change after creation, preventing accidental errors.
• Allow objects to be used as dictionary keys or set elements, as they are hashable.
• Simplify working with multithreading, as immutable objects are safe for parallel access.

Example:

s = "hello"
# s[0] = 'H'  # Error, strings are immutable

# To change a string, create a new one
s = 'H' + s[1:]