Navigating Python’s Data Types: Immutability vs. Mutability Explained

Discover the difference between mutable and immutable data types in Python

Max N
3 min readMar 21, 2024

One fundamental concept every Python developer must grasp is the distinction between mutable and immutable data types. While seemingly trivial, mismanaging these variables can lead to perplexing bugs and suboptimal performances. Fear not, though — this comprehensive guide delves into the nuances of Python’s mutable versus immutable data types, providing practical examples along the way.

Defining Mutable and Immutable Objects

Mutable objects refer to those whose internal state can change after creation, enabling modification throughout their lifetime. Examples include lists, dictionaries, and custom class instances. On the contrary, immutable objects possess fixed properties upon instantiation, preventing alterations once initialized. Common examples encompass tuples, strings, and primitive data types like integers, floats, and booleans.

Let’s examine these definitions via code snippets:

Mutable Example: Lists

fruits = ["apple", "banana"]
fruits.append("cherry")
print(fruits) # Output: ['apple', 'banana', 'cherry']

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Max N

A writer that writes about JavaScript and Python to beginners. If you find my articles helpful, feel free to follow.