Abstract. This article discusses the principles of Object-Oriented Programming (OOP) in the C++ programming language and their practical application. OOP is one of the important areas of programming technologies, which allows organizing the program structure in a modular form, reusing code, and simplifying complex software systems. The article discusses the four main principles of OOP - encapsulation, inheritance, polymorphism, and abstraction - with theoretical and practical examples. It also discusses methods for modeling real-life processes using classes and objects in the C++ language.