Object-oriented programming (OOP) is a technology used for software development. OOP facilitates component programming with its standards. C# is a language based on OOP. There are many objects available in C#, and programs are written using these objects. Additionally, we can write our own class. OOP has three principles: Encapsulation Inheritance Polymorphism Encapsulation: It refers to the information and operations about an object. These operations, called methods and properties, reveal the characteristics of the object, such as the color and size of a car. Inheritance: It is the creation of an object based on another object, with the new object being influenced by the parent object. For example, a computer is composed of parts, and the parts are influenced by the full object of the computer. Polymorphism: It is the use of a specific operation by multiple objects. Object-Oriented Programming in PHP To understand object-oriented programming in PHP, it is necessary to have a thorough knowledge of functions and variables, which are the basic building blocks of PHP. We use the class command to create a class. Let\'s create a file named class.php <?php class Computer{ } ?> Our class is empty. After this, we cannot do anything other than variable declaration and function declaration here. The logic here is that we need to write a function specific to the class we are going to write and call the necessary function where necessary. It would not be appropriate to write a database class and then write a function to produce graphical statistics within it. <?php class Computer{ public $brand, price; function defineBrand($newBrand){ $this->brand = $newBrand; } function showBrand(){ return $this->brand; } } ?> We have created the functions defineBrand() and showBrand(). You can understand from the names what they do. Here, a special reference variable, $this->, is different from general usage. We use the $this-> expression to access a variable and access other functions of the current class.With $this->brand = $newBrand, we assigned the value of $newBrand to the variable $brand, and with return $this->brand, we return the $brand variable. Now, let\'s create an index.php file and include the class.php file. <?php include \'class.php\'; ?> We only called the class.php file, but we are not using the computer object inside it yet. So let\'s continue. <?php include \'class.php\'; $computer = new Computer(); ?> I assigned the computer object to the $computer variable. Think of this variable as a handle; we can hold and control the cup with it. <?php include \'class.php\'; $computer = new Computer(); $computer->defineBrand(\'HP\'); echo $computer->showBrand(); ?> We defined the brand with the defineBrand function and printed it to the screen with showBrand. We did all of these with the class and its methods. In PHP, object-oriented programming is generally done like this.This topic is not limited to these, it\'s a very deep topic, I just wrote it for introductory purposes.