Introduction to Object-Oriented Programming (OOP) in Python

Object-Oriented Programming (OOP) is a programming paradigm based on the concept of “objects” — data structures that contain data (attributes) and functions (methods) to operate on that data.

Python supports OOP and allows you to design code that is modular, reusable, and easier to maintain.

Key Concepts of OOP

Concept	Meaning
Class	A blueprint for creating objects
Object	An instance of a class
Attribute	Data stored in an object
Method	Function defined inside a class
Encapsulation	Hiding internal state and requiring all interaction through methods
Inheritance	One class can inherit attributes and behavior from another class
Polymorphism	Objects of different classes can be treated as objects of a common superclass

Why Use OOP?

Benefit	Description
Modular Code	Divide code into logical parts
Reusability	Define classes once, reuse multiple times
Easier Maintenance	Change in one place affects all objects of that class
Scalability	More natural for complex software design

How OOP Works in Python

You define a class using the class keyword.
You create objects (instances) from the class.
You can add attributes and methods to represent object state and behavior.

Example 1: Basic Class Definition

oop_intro_class.py

class Person:
    def greet(self):
        print("Hello!")
 
p = Person()
p.greet()

output.txt

Hello!

Example 2: Class with Attributes and Methods

oop_intro_attributes.py

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
 
    def introduce(self):
        print(f"My name is {self.name} and I am {self.age} years old.")
 
p1 = Person("Alice", 30)
p1.introduce()

output.txt

My name is Alice and I am 30 years old.

Example 3: Multiple Objects from the Same Class

oop_intro_multiple_objects.py

class Car:
    def __init__(self, model, year):
        self.model = model
        self.year = year
 
    def display_info(self):
        print(f"Model: {self.model}, Year: {self.year}")
 
car1 = Car("Tesla Model S", 2022)
car2 = Car("Ford Mustang", 2020)
 
car1.display_info()
car2.display_info()

output.txt

Model: Tesla Model S, Year: 2022
Model: Ford Mustang, Year: 2020

How Does OOP Improve Code Quality?

Advantage	Example
Logical grouping of data + behavior	Class `Car` has both `model` and `display_info()`
No need for global variables	Each object stores its own state
Reduced code duplication	Methods shared across all objects of a class
Easier to understand large codebases	Each class serves one responsibility

Summary

OOP allows you to build software using objects.
An object is an instance of a class.
Objects contain attributes (data) and methods (behavior).
OOP makes Python programs modular, reusable, and scalable.

Next, we will dive deeper into Classes and Objects — how to define them, how they work, and how you can use them to structure your Python programs.

Installing Packages Classes and Objects