What are mutable and immutable types in Python?

A mutable object can be changed after it is created, and an immutable object cannot. When you “change” an immutable value, Python actually creates a new object.

Mutable	Immutable
list, dict, set	int, float, bool, str, tuple, frozenset

numbers = [1, 2]
numbers.append(3)
print(numbers)

text = "hi"
print(text.upper())
print(text)

text[0] = "H"

Output:

The list was changed in place, but the string stayed the same, and upper() gave a new string. This matters when you pass a list to a function, because the function can change the original list. See Python Data Types.

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