What is object-oriented programming?


4 min read

You’ll encounter object-oriented programming while learning languages such as Java, Python, and C#. It’s all about modularization, that is, dividing code into parts. Let’s find out if object-oriented programming is easy to learn and compare it with procedural programming.

It’s best not to wait too long to learn object-oriented programming. Our flagship full-stack development course usually introduces it after the third month of learning. Why?

Because waiting longer would mean you’d have to get rid of habits already. Habits that make it harder to grasp object-oriented programming. Of course, an essential part of learning object-oriented programming is theory. You can sit through the lectures, but not everyone can learn that way effectively. That’s why at Codecool, we focus so much on practice-based learning. We teach everything through real examples, and object-oriented programming is no exception. We know that young programmers learn best by doing – that’s how they encounter new challenges and how things fall into place.

It can take time to grasp the essence of object-oriented programming. One must first collide with a more extensive, more complex program to understand it. When you write a simple program, like a calculator, object-oriented programming won’t be helpful – in the case of simple console programs, it could even add to the workload.

Definition of object-oriented programming

In most publications, you will read that with object-oriented programming, you can reflect upon real objects that occur in reality with code. This is only partially true. According to Robert Martin (known online as Uncle Bob), a mentor of object-oriented programming and clean code, the above definition of object-oriented programming was created by marketers.

When the first object-oriented languages were born, marketing professionals wanted to encourage supervisors to support it. And it was easiest to explain this new type of programming with a simple description: object-orientedness is about reflecting on real objects with code. And the promise was, that it will make programming faster, ergo, more profitable.

So what is object-oriented programming really? It’s time for a more adequate, albeit less catchy, definition. That is: object-oriented programming allows us to modularize our code. But what does it mean to modularize?

Modularization can be simply explained as dividing code into small “building blocks” – of universal shape, which can be used in different places. We can put together a house, a castle, or an airplane from such building blocks – in other words, any program we can think of.

In which programming languages will you have to deal with object-oriented programming?

The most popular object-oriented language today is Java. Although we associate it mainly with object-orientedness, we can also write a program in it procedurally. Python, too, is an object-oriented language, although it can be written procedurally. The C language, on the other hand, is closely associated with procedural programming. Objectivity appeared only with the introduction of the C++ language.Find out more:

5+1 Most wanted programming languages.


Java is a language that has greatly popularized object-oriented programming. It consistently approaches the subject of objectivity and fully implements it – this is done in accordance with the theory. On the one hand, it allows us to obtain clean, object-oriented correct code. For some programmers, however, it becomes cumbersome. Silking on full object-oriented compliance slows down their work, so they consider crystal-clear code art for art’s sake.


PHP is an object-oriented language since it’s often the object of jokes. Just kidding. This is only a long-running joke among programmers, and we can’t quite agree with it. Fact is, PHP had a difficult start with objectivity. First, it was a scripting language, and objectivity was only starting to be introduced, following in the footstep of the Java-model.


When we start programming in Python, we don’t have much to do with objectivity – we often write shorter programs without using them at all. Python is similar to PHP in terms of object-orientedness, but there are some issues to watch out for when switching from Java to Python.


The creation of the C# language was strongly inspired by Java. The programmers who created C# valued Java but wanted to write a language that would not contain poorly designed functionality. The core, related to object-oriented programming, is very similar to Java. Some things are called differently, but there are a lot of standardized parts.


The history of JavaScript is somewhat similar to the history of PHP – JavaScript is also a language that was slow to become object-oriented. In previous versions of JavaScript, this aspect was practically absent; it took a long time to develop it. It wasn’t until 2015 that the ECMAScript standard came in, which redefined the JavaScript language and introduced strictly object-oriented notation into it. Only recently have browsers begun to support the standard. JavaScript programmers felt the lack of object-orientedness and had already begun to deal with it – so so-called JavaScript language supersets were created, such as TypeScript, created by Microsoft, which introduced object-orientedness into JavaScript similar to how we know it from C#.

You will also be interested in: 5 reasons to learn JavaScript

Object-oriented vs. structured programming

Before object-oriented programming was developed, procedural (structured) programming was common. At the time, programming often consisted of copying and pasting code fragments, making the code much more confusing. Procedural programming was found in the C language, among others. At this point, when we program in an object-oriented way, we package the pieces of our system into blocks that perform the functions. And we just put them together. When one doesn’t work for us, we can replace it with another. In procedural programming, this was not so easy and resembled an open heart surgery.


The theory of object-oriented programming is universal to all programming languages. The object-oriented programming paradigm is not entirely tied to the language itself – as we have shown, procedural programming is still present, and in the most prominent languages, associated mainly with objectivity. So it is impossible to stay with learning only one way of programming – for simple programs we will choose procedural programming, and for larger and more complex projects – object-oriented.

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