What Is Object-Oriented Programming? Most Important Details to Know About OOP

Are you interested in learning about object-oriented programming (OOP)? Check out this guide for the definition of OOP, the difference between class and object, how to learn OOP for free, and more. Object-oriented programming languages are some of the most popular in the tech industry, so you should learn at least one if you want to get a great job in tech.

What Is Object-Oriented Programming (OOP)? 

Object-oriented programming, abbreviated as OOP, is a type of programming that focuses on classes and objects. It is most often used to structure software programs into simple, reusable pieces of complex code to create individual objects. Object-oriented programming techniques can help you succeed as a programmer.

OOP is the most popular programming paradigm. The other paradigms are procedural, functional, and logical. OOP is popular because it allows you to break down software into simpler problems to solve. OOP can be used through different programming languages, including Java, C++, Python, C#, and Ruby.

What Is the Difference Between Class and Object in Object-Oriented Programming?

Get offers and scholarships from top coding schools illustration

Find Your Bootcamp Match

  • Career Karma matches you with top tech bootcamps
  • Access exclusive scholarships and prep courses

By continuing you agree to our Terms of Service and Privacy Policy, and you consent to receive offers and opportunities from Career Karma by telephone, text message, and email.

A class is a logical construct or a template, and an object is a physical element. It is important to understand the difference if you want to learn OOP. A class definition is a group of variables and methods that does not allocate memory space. It includes a child class and a parent class, also known as a base class.

Classes contain functions available to objects of that type, which vary depending on the type of object. It marks a category of objects and acts as a template for creating those objects. It defines the behaviors and properties of an object. Class hierarchy is helpful when needing to manage a range of classes and users.

An object is a physical element. It is a member or instance of a class. For example, an individual object could be a pen, keyboard, or mouse. Objects are organized by class to help create clean, readable, and usable code. There are many class methods in OOP and other concepts like abstract classes, derived class, and more.

What Are the Main Object-Oriented Programming (OOP) Concepts?

There are four key pillars of object-oriented programming: encapsulation, abstraction, inheritance, and polymorphism. These principles of object-oriented programming are listed and explained below.


Encapsulation is the bundling of data and associated methods into a single unit, like classes. A helpful way to think about encapsulation is by comparing it to a pill capsule. A pill capsule is often used to contain combinations of different medicines. Encapsulation in OOP contains combinations of data and methods to use that data. 


Abstraction is the sector of OOP that focuses on essential attributes while hiding less important information. This hides unnecessary details from the users to make their experience more enjoyable. 

To better understand abstraction, we can relate it to driving a car. You know that pushing the accelerator will increase the speed, but it is not necessary to know what is happening with the engine when the accelerator is pressed. 


Inheritance is the process in OOP where one class inherits attributes or methods of another class. This facilitates the reusability of OOP. Class inheritance works by starting with the base class, which is responsible for the preceding classes. Base classes allow the parent class to pass its behaviors to the child classes.

Think of inheritance as a child inheriting traits from their parents. If the mother and father both have brown eyes, it is likely for the child to have brown eyes as well. The same goes for a parent class and a child class in object-oriented programming.


Polymorphism is the ability to have many forms and characteristics. In OOP, this means that different classes can be used with the same interface. For example, an individual may be a mother, wife, daughter, and teacher all at the same time. This individual is not four separate entities, but rather one entity with multiple forms or characteristics.

Why Object-Oriented Programming?

Object-oriented programming is an important concept to learn because it is widely used by developers in all industries. Learning OOP is a great choice because it is simple, flexible, popular, and modular. Read below for more benefits of learning OOP.

  • Simplicity. OOP is fairly easy to learn and can be used with a variety of programming languages. OOP allows you to complete actions in programming. It makes the actions simple and hides the complex details.
  • Flexibility. OOP is also very flexible. You can modify functions already created in OOP to fit different use cases. It is also used for many jobs. With OOP skills, you can become a systems engineer, web designer, database developer, and more.
  • Popularity. Object-oriented programming can help you get a job in tech. According to the Bureau of Labor Statistics, software developers earn an average salary of $110,140. This means that OOP can help you earn a high salary.
  • Modularity. Modularity means the program as a whole can be separated into clusters or groups that interact among themselves. This is another way OOP allows for simplicity and flexibility. You can rearrange or edit modules of the program depending on the situation.

5 Most Popular Object-Oriented Programming Languages in 2021

Most of the popular programming languages today are object-oriented languages. These include web development languages like Java and Ruby. Take a look below at a basic list of the top five OOPs and read about them in more detail.

  1. Java
  2. C++
  3. Python
  4. C#
  5. Ruby


Java is a very popular object-oriented programming language. It is a server language used for big data and development projects. It is also common in numerical, desktop, and mobile computing. Java is very easy to learn, and it can run on many different platforms and types of computers. 


C++ is used to develop games, operating systems, and browsers. C++ works with procedural, functional, and object-oriented programming. It is popular because it can efficiently run and manage memory. C++ is a difficult language to master. It does share similar elements with other programming languages.


Python is a general-purpose, object-oriented programming language. It can be used for web development, artificial intelligence, and machine learning. It is also used for design and analytics. Python is a very popular language due to its simplified syntax. This means that you can learn how to use Python easily.


C# is a modern object-oriented programming language. It is commonly used in game development and application creation. C# allows developers to create secure applications. It is an easy language to read, but it may take more time to learn compared to simpler languages like Python. 


Ruby is a popular object-oriented scripting language that simplifies repetitive tasks for developers. This is used most often for web applications. It is very similar to Python and can be used in data analysis, prototyping, and more. Ruby is an easy language for beginners, especially when used with the Rails framework.

10 Best Object-Oriented Programming Online Courses 2021: Learn OOP

If you want to learn object-oriented programming, there are hundreds of online courses out there. It can be difficult to choose the right one for you, even if you know what OOP language you want to learn. Check out the best online courses for object-oriented programming below.

  1. Basics of Object-Oriented Programming with C# by Udemy
  2. Introduction to Object-Oriented Programming with Java by edX
  3. Introduction to Ruby by Codecademy
  4. Object-Oriented Java Programming: Data Structures and Beyond Specialization by Coursera
  5. Object-Oriented Programming, Part I & II by Codecademy
  6. OOP in C++: 2020 by Skillshare
  7. OOP for Java Interviews by Udemy
  8. OOP in Python: Create Your Own Adventure Game by FutureLearn
  9. Python OOP by Udemy
  10. Software Construction: Object-Oriented Design by edX

Basics of Object-Oriented Programming with C# by Udemy 

  • Duration: 1 hour, 35 minutes
  • Cost: Free

This is a free beginner course offered by Udemy. This class teaches the basics of OOP with C#, but the concepts can be applied to most languages. This course will give you a foundation for complex, systematic, and clean programming methods. In the end, you will build a project to practice what you have learned.

Introduction to Object-Oriented Programming with Java by edX

  • Duration: 5 months
  • Cost: $537

This course is offered through edX with Georgia Tech. This is a professional certificate course. You will learn the basics of Java, OOP, and algorithms. You will also discover how to create and implement exceptions, data structures, and graphical user interfaces. It is a self-paced course that offers expert instruction in three segments.

Introduction to Ruby by Codecademy

  • Duration: 1 hour
  • Cost: Free

This is one section of a ten-lesson program in learning Ruby. This particular course is an introduction to Ruby. It is one object-oriented language that can be used independently or as part of a framework. The course covers commenting code, arithmetic operations, and other Ruby commands.

Object-Oriented Java Programming: Data Structures and Beyond Specialization by Coursera

  • Duration: 7 months
  • Cost: Coursera Membership

This course is offered by the University of California San Diego and Coursera. It discusses topics in software development. You will learn OOP principles that will help you strengthen and utilize your Java skills. It also includes a hands-on project to put your skills into practice and earn a certificate. 

Object-Oriented Programming, Part I & II by Codecademy

  • Duration: 1 hour
  • Cost: Free

These two sections are part of the previously mentioned ten-lesson program. Part I teaches you how to organize information and behavior using Ruby’s concepts. Part II details more advanced elements of OOP in Ruby such as modules, mixins, and methods. Paired together, these courses can teach you all the basics of Ruby.

Object-Oriented Programming in C++: 2020 by Skillshare

  • Duration: 8 hours, 47 minutes
  • Cost: Skillshare Membership

This course is offered through Skillshare. To do well in this course, you should be familiar with the basics of C++. In this class, you will explore abstraction, encapsulation, inheritance, and polymorphism. It will also help you improve your code writing and problem-solving skills. By the end of this course, you should be ready to perform in the industry. 

Object-Oriented Programming (OOPs) for Java Interviews by Udemy

  • Duration: 13 hours
  • Cost: Free

This course, offered through Udemy, teaches the essential concepts of OOP. It covers class, objects, inheritance, abstraction, and composition. Basic knowledge of Java is preferred but not required. It is offered via on-demand video classes. This course does not offer an official certificate, but it is a great way to boost your Java skills.

Object-Oriented Programming in Python: Create Your Own Adventure Game by FutureLearn 

  • Duration: 4 weeks
  • Cost: Free, $49 for certificate

This introductory course is free and self-paced. It provides you with an introduction to OOP by showing you how to create objects, methods, functions, and classes. You will then use this knowledge to create your own adventure game that you can share with other learners. This course was developed by the Raspberry Pi Foundation.

Python OOP – Object-Oriented Programming for Beginners by Udemy

  • Duration: 2 hours
  • Cost: $12.99

This course from Udemy teaches you how to structure code using class and objects. It helps you learn four key elements of OOP. These elements are abstraction, encapsulation, polymorphism, and inheritance. You will finish the course with practice with real-world issues and knowledge of how to write your own programs.

Software Construction: Object-Oriented Design (OOD) by edX 

  • Duration: 6 weeks
  • Cost: Free, $125 for a certificate

This course offered by edX and the University of British Columbia focuses more on object-oriented design (OOD), which is part of the process for OOP. You will learn the principles of OOD along with abstraction techniques and design patterns. This will enable you to use these techniques to build an application. 

What Are Some Criticisms of Object-Oriented Programming?

A desk with a small stack of books on the left and a laptop with programming text on the screen. What Is Object-Oriented Programming

Like every programming paradigm, object-oriented programming isn’t perfect.

Object-oriented programming has been criticized for issues such as size, execution time, and memory leaks. Even though it can be easy to learn and important to know, OOP is not useful for everything. Read below to learn more about the cons of object-oriented programming.

  • Size. OOP programs tend to be larger than programs developed with the other programming paradigms. This can make object-oriented programs difficult to work with and share. 
  • Time. Again, due to the size of OOP programs, they also take more time to perform and execute their designated actions. This can be inconvenient and frustrating for the user.
  • Memory Leaks. Memory leaks happen because the program sets aside resources, like storage and memory, that aren’t used. This can lead to unnecessary memory and storage use, which can take up too much space on a computer.

Object-Oriented Programming FAQ

What is the difference between OOD and OOP?

Object-oriented design is done through an object-oriented methodology to design a computer system or application. OOD is part of the process for OOP. OOD allows for software solutions to be implemented based on objects.

What are the benefits of OOP compared to other programming styles?

OOP can make the development and maintenance of programs easier compared to other programming styles like procedural programming or functional programming. OOP also hides unnecessary data, making it more user-friendly.

Is OOP outdated?

OOP is not outdated yet. However, it is becoming less universal. This happens with most technology. As other tools come into play, OOP may start to take a backseat, but it is still very popular. 

What careers use OOP?

If you are working with code, chances are you’ll use object-oriented programming. You can work in software design, cyber security, web development, or even software engineering. Some specific examples include software developers and engineers, application developers, and front end or backend engineers.

Popular Bootcamps

Find a training program that will help you start your tech career journey.


Get matched to top coding bootcamps

By continuing you indicate that you have read and agree to Online Degree Hero Privacy Policy

Powered By
Career Karma



You don't have permission to register