Python Basic Class Example (OOP)

This page shows a simple Python class example for beginners.

You will learn how to:

Create a class
Make an object from that class
Store data in attributes
Add behavior with a method
Use __init__ to set starting values

If you are new to classes, this is a good first example because it uses a small real-world idea and keeps the code short.

Quick example

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

    def bark(self):
        print(f"{self.name} says woof!")

my_dog = Dog("Max", 3)
print(my_dog.name)
print(my_dog.age)
my_dog.bark()

Output:

Max
3
Max says woof!

Use this as your first working class example. It shows:

A class
An __init__ method
Attributes
An object
A method call

What this example teaches

This example helps you understand these basic OOP ideas:

A class is a template or blueprint
An object is one thing created from that class
Attributes store data for the object
Methods define what the object can do
__init__ sets the starting values when the object is created

If you want a fuller beginner explanation, see Python classes and objects explained.

The example class

Here is the full class again before we break it down:

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

    def bark(self):
        print(f"{self.name} says woof!")

This class uses:

Dog as the class name
name and age as the two attributes
bark() as the one method

This is a good beginner example because it is small and easy to read.

How the `init` method works

The __init__ method runs when you create a new object.

In this example:

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

Here is what each part means:

__init__ is the special method Python uses to set up a new object
self refers to the current object
name and age are values passed in when the object is created
self.name = name stores the value in the object
self.age = age stores the age in the object

So if you create Dog("Max", 3), Python does this setup:

name becomes "Max"
age becomes 3
self.name is set to "Max"
self.age is set to 3

If self feels confusing, see the __init__ method in Python explained.

How to create an object

You create an object by calling the class name like a function:

my_dog = Dog("Max", 3)

This means:

Dog is the class
my_dog is the object
"Max" and 3 are passed into __init__

You can create more than one object from the same class:

dog1 = Dog("Max", 3)
dog2 = Dog("Bella", 5)

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

Output:

Max
Bella

Both objects use the same class, but each object can store different values.

You can learn more in how to create an object in Python.

How to access attributes and call methods

Use dot notation to work with object data and behavior.

Read attributes

my_dog = Dog("Max", 3)

print(my_dog.name)
print(my_dog.age)

Output:

Max
3

This reads stored data from the object.

Call a method

my_dog = Dog("Max", 3)
my_dog.bark()

Output:

Max says woof!

This runs behavior defined in the class.

Data vs behavior

my_dog.name reads data
my_dog.age reads data
my_dog.bark() runs a method

If you want more method examples, see basic methods in Python classes explained.

Step-by-step code breakdown

Let’s go through the main lines one by one.

`class Dog:`

class Dog:

This creates a new class named Dog.

Think of it as a blueprint for making dog objects.

`def init(self, name, age):`

def __init__(self, name, age):

This defines the setup method for new objects.

When you create a Dog, Python runs this method automatically.

`self.name = name`

self.name = name

This creates an attribute named name on the object.

The value passed in becomes part of that object.

`def bark(self):`

def bark(self):
    print(f"{self.name} says woof!")

This defines a method named bark.

It uses self.name so the message matches the current object.

`my_dog = Dog("Max", 3)`

my_dog = Dog("Max", 3)

This creates one Dog object and stores it in the variable my_dog.

At that moment:

self.name becomes "Max"
self.age becomes 3

Common beginner mistakes

Here are some common problems beginners run into with classes.

Forgetting `self` in method definitions

Wrong:

class Dog:
    def bark():
        print("Woof!")

Right:

class Dog:
    def bark(self):
        print("Woof!")

Inside a class, instance methods need self as the first parameter.

Forgetting parentheses when creating an object

Wrong:

my_dog = Dog

Right:

my_dog = Dog("Max", 3)

Without parentheses, you are referring to the class itself, not creating an object.

Using a method name without `()` when trying to call it

Wrong:

my_dog.bark

Right:

my_dog.bark()

Without (), Python gives you the method itself instead of running it.

Misspelling attribute names

Wrong:

print(my_dog.nam)

Right:

print(my_dog.name)

A misspelled attribute name can cause an AttributeError: object has no attribute.

Bad indentation inside the class

Wrong:

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

Right:

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

Python uses indentation to understand code blocks. Bad indentation can cause an IndentationError: expected an indented block.

Try it yourself

Once the basic example works, try these small changes:

Change the object values
Create a second Dog object
Print both objects' data
Add another method such as birthday()

Example:

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

    def bark(self):
        print(f"{self.name} says woof!")

    def birthday(self):
        self.age += 1
        print(f"{self.name} is now {self.age}")

dog1 = Dog("Max", 3)
dog2 = Dog("Bella", 5)

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

dog1.birthday()

Output:

Max 3
Bella 5
Max is now 4

This is a good next step after learning the basic example.

Common causes of confusion

Beginners often get stuck on these points:

Confusing a class with an object
Not understanding what self refers to
Mixing up attributes and methods
Indentation mistakes inside the class body
Calling methods with missing required arguments

If that happens, test one small part at a time and print values often.

Useful debugging checks:

print(type(my_dog))
print(my_dog.name)
print(my_dog.age)
dir(my_dog)
help(Dog)

These can help you see:

What type my_dog is
Whether attributes exist
What names and methods are available on the object

FAQ

What is the difference between a class and an object?

A class is a blueprint. An object is one created item based on that blueprint.

Why do I need `self` in a class?

self lets Python refer to the current object so each object can store its own data.

Is this page teaching all of OOP?

No. This page focuses on one simple class example. Broader OOP concepts belong on separate learn pages.

Can a class have more than one method?

Yes. A class can have many methods, but this example stays small to make the core idea clear.