What is inheritance and how does it work in Python?

Inheritance is an OOP mechanism where a child class inherits attributes and methods from a parent class.

Basic inheritance:

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

    def speak(self):
        return f"{self.name} makes a sound"

class Dog(Animal):
    def speak(self):
        return f"{self.name} says: Woof!"

class Cat(Animal):
    def speak(self):
        return f"{self.name} says: Meow!"

dog = Dog("Bobik")
print(dog.speak())  # Bobik says: Woof!

super() — calling a parent method:

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

class Dog(Animal):
    def __init__(self, name, age, breed):
        super().__init__(name, age)  # Call parent's __init__
        self.breed = breed

dog = Dog("Bobik", 3, "Labrador")
print(dog.name, dog.breed)  # Bobik Labrador

Checking inheritance:

print(isinstance(dog, Dog))     # True
print(isinstance(dog, Animal))  # True
print(issubclass(Dog, Animal))  # True

Overriding methods:

A child class can replace or extend a parent's method:

class Shape:
    def area(self):
        return 0

class Rectangle(Shape):
    def __init__(self, width, height):
        self.width = width
        self.height = height

    def area(self):
        return self.width * self.height

rect = Rectangle(5, 3)
print(rect.area())  # 15

Multiple inheritance:

Python supports inheriting from multiple classes. The method lookup order is determined by the MRO (Method Resolution Order) algorithm, which can be inspected via ClassName.mro().