abstract base class (ABC)

In Python, an abstract base class (ABC) is a class that can’t be instantiated on its own and is designed to be a blueprint for other classes, allowing you to define a common interface for a group of related classes.

ABCs allow you to define methods that must be created within any subclasses built from the abstract base class. This is useful for ensuring that derived classes implement particular methods from the base class, providing a consistent interface for different parts of your program.

To define an abstract base class, you inherit from abc.ABC and use the @abstractmethod decorator to mark methods that must be implemented by subclasses. Attempting to instantiate an abstract base class or a subclass that hasn’t implemented all abstract methods will raise a TypeError exception.

Example

Here’s a simple example of how to define and use an abstract base class in Python:

Python animals.py 
from abc import ABC, abstractmethod

class Animal(ABC):
    @abstractmethod
    def speak(self):
        pass

    def jump(self):
        return f"{self.__class__.__name__} is jumping"

Animal is an abstract base class with an abstract method .speak() and a regular method .jump(). Subclasses must implement all methods marked with @abstractmethod:

Python 
>>> from animals import Animal

>>> class Dog(Animal): pass
...

>>> Dog()
Traceback (most recent call last):
    ...
TypeError: Can't instantiate abstract class Dog
    without an implementation for abstract method 'speak'

Here’s a correct implementation:

Python 
>>> class Dog(Animal):
...     def speak(self):
...         return "Woof Woof"
...

>>> dog = Dog()
>>> dog.speak()
'Woof Woof'

>>> dog.jump()
'Dog is jumping'

Dog is a concrete class that inherit from Animal and implement the .speak() abstract method. It inherits the .jump() methdo from Animal.

Implementing an Interface in Python

Tutorial

Implementing an Interface in Python

In this tutorial, you'll explore how to use a Python interface. You'll come to understand why interfaces are so useful and learn how to implement formal and informal interfaces in Python. You'll also examine the differences between Python interfaces and those in other programming languages.

advanced python

For additional information on related topics, take a look at the following resources:

By Leodanis Pozo Ramos • Updated Jan. 30, 2025 • Reviewed by Dan Bader
Python Glossary Share Feedback