Python Classes and Objects: A Beginner’s Guide (2026)

When you first learn Python, you usually start with variables, loops, and functions. These tools help you write simple programs and understand how the language works. But as your programs grow, managing many related variables and functions can quickly become confusing. This is why Python classes are so useful.

Python classes help you group related data and functions together in one unit. This makes your programs cleaner, easier to understand, and reusable. Classes are used in web development, data science, automation, and many real world projects.

In this guide, you will learn:

• What a Python class is
• What an object is
• How to create classes and instances
• The difference between class and instance variables
• How special methods like __init__() and __str__() work
• A simple example of inheritance

By the end, you will understand how Python classes work and how to start using them in your own programs.

Why Python Classes Matter

As your Python programs get bigger, using only variables and functions becomes messy. Imagine you want to track information for multiple users in an app. You could create separate variables for each user’s name, email, and age. But if you have 100 users, it would be nearly impossible to manage all that data.

Python classes solve this problem. They let you bundle related data and behavior into one blueprint. This blueprint can then be used to create multiple objects, each representing one instance of that blueprint.

Think of a class as a cookie cutter and an object as the cookie you bake. The cookie cutter defines the shape, but each cookie you make can have its own toppings or colors. Similarly, the class defines the structure, and each object can hold its own unique data.

What Is a Class in Python?

A class is a blueprint for creating objects. It defines:

• Attributes – the data or properties that an object has
• Methods – the actions or functions that an object can perform

Here is a simple example:

class Dog:
    sound = "bark"

This creates a class named Dog. The variable sound is called a class attribute. All dogs will share this sound unless it is changed for a specific object.

Note: If you set dog1.sound = "woof", you are not changing the class attribute. You’re creating a new instance attribute on dog1 that overrides (shadows) the class attribute for that one object. The Dog.sound value stays the same.

dog1.sound = "woof"
print(dog1.sound)   # woof (instance override)
print(dog2.sound)   # bark (still using class attribute)
print(Dog.sound)    # bark (class attribute unchanged)

What Is an Object?

An object is an instance of a class. An instance is a specific version of that class with its own data.

You can create many objects from the same class:

class Dog:
    sound = "bark"

dog1 = Dog()
dog2 = Dog()

print(dog1.sound)
print(dog2.sound)

Output:

bark
bark

Here:

• Dog is the class
• dog1 and dog2 are objects
• Each object is an instance of Dog

The dot operator . is used to access attributes and methods of class objects.

The __init__() Constructor

The __init__() method is called a constructor. It runs automatically when you create a new object.

The constructor is used to give each object its own instance variables. Instance variables hold data that is unique to that object.

class Dog:
    def __init__(self, name, age):
        self.name = name
        self.age = age

dog1 = Dog("Buddy", 3)
dog2 = Dog("Charlie", 5)

print(dog1.name)
print(dog2.age)

Output:

Buddy
5

Why self matters:

• self refers to the current object
• It allows each object to store its own data
• Without self, Python wouldn’t know which object’s data you are working with

Think of self like a label on each dog. Each dog object can carry its own label (data) separate from others.

Class Variables vs Instance Variables

Variables in a class can be either class variables or instance variables.

Class Variables

Class variables are shared across all objects of a class. They are defined outside any method.

class Dog:
    species = "Canine"  # Class variable

    def __init__(self, name, age):
        self.name = name  # Instance variable
        self.age = age  # Instance variable

dog1 = Dog("Buddy", 3)
dog2 = Dog("Charlie", 5)

print(dog1.species)  # Class variable
print(dog2.species)  # Class variable

Output:

Canine
Canine

Instance Variables

Instance variables belong to each object and are defined inside __init__().

dog1.name = "Max"

print(dog1.name)
print(dog2.name)

Output:

Max
Charlie

Each object keeps its own copy of instance variables. Changing one does not affect the other.

Common gotcha: Be careful using mutable values (like lists or dictionaries) as class variables. They are shared across all objects, so changing them for one object affects the others.

class Dog:
    tricks = []  # shared class variable (mutable)

    def __init__(self, name):
        self.name = name

dog1 = Dog("Buddy")
dog2 = Dog("Charlie")

dog1.tricks.append("sit")

print(dog1.tricks)  # ['sit']
print(dog2.tricks)  # ['sit']  (surprising!)

If you want each object to have its own list or dictionary, create it inside __init__() so that you create an instance variable, like so:

class Dog:
    def __init__(self, name):
        self.name = name
        self.tricks = []  # instance variable (separate per object)

The __str__() Method

The __str__() method allows you to define a readable string representation for an object. Without it, printing an object looks like:

print(dog1)

Output:

<__main__.Dog object at 0x123456>

Example of how to use __str__():

class Dog:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def __str__(self):
        return f"{self.name} is {self.age} years old."

dog1 = Dog("Buddy", 3)
dog2 = Dog("Charlie", 5)

print(dog1)
print(dog2)

Output:

Buddy is 3 years old.
Charlie is 5 years old.

Inheritance in Python

Inheritance allows one class to reuse code from another class.

• The original class is called the parent class
• The new class is called the child class

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        print("Some sound")

class Dog(Animal):
    def speak(self):
        print("Woof")

dog1 = Dog("Buddy")
print(dog1.name)  # Uses inherited attribute
dog1.speak()  # Uses overridden method

Output:

Buddy
Woof

Inheritance avoids repeating code and allows child classes to add their own behavior.

What's Next in Your Python Programming Journey

You've learned the fundamentals of Python classes. You now know how to create blueprints, instantiate objects, and use inheritance to reuse code. As you continue learning, you'll discover more advanced concepts like polymorphism (using the same method name across different classes) and abstraction (hiding complex implementation details).

If you're ready to take your Python skills further, Dataquest's Introduction to Python Programming course teaches these concepts step-by-step with hands-on practice. You'll learn:

• Variables, loops, and functions
• Object-oriented programming fundamentals
• Classes, objects, and inheritance
• Real-world Python projects to build your portfolio

Our online Python courses include guided projects so you can write real Python code from day one. Start with the basics and progress naturally to advanced topics like polymorphism, abstraction, and design patterns.

Final Thoughts

Python classes are a key part of writing organized and reusable code. A class is a blueprint and an object is a specific instance built from that blueprint.

By learning the Python basics such as attributes, methods, constructors, class variables, instance variables, and inheritance, you will have a strong foundation for building Python programs.

Start small and practice creating your own Python classes. As you use them in real projects, these concepts will start to feel natural, and you will find it easier to write clean and efficient Python code.