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.

See also #

• Python classes and objects explained
• Object-oriented programming in Python explained
• The __init__ method in Python explained
• How to create a class in Python
• How to add methods to a class in Python

After you understand this example, the next good step is to create your own class and then learn __init__ and methods in more detail.