Mutability in Python

We say an object is mutable if its value can be changed after it has been created. An object is immutable if its value is fixed when it is created and can never be changed. Immutable values are, in effect, read-only values. In this chapter, we will look at mutability in Python and the pros and cons of both types of objects.

Mutability

In Python, it is usually an object’s type that tells you whether it is mutable or not. For example, lists are mutable. If you create a list, you can change it in various ways, as shown here: