What are the four core principles of OOP?

The four core principles of Object-Oriented Programming (OOP) are encapsulation, inheritance, polymorphism, and abstraction.

Encapsulation is the principle that binds together the data and functions that manipulate the data, and keeps both safe from outside interference and misuse. In other words, it is the mechanism of hiding the data and exposing only the methods needed to interact with the object's data. This principle is crucial in maintaining the integrity of the data within the object and preventing unauthorized access.

Inheritance is a mechanism that allows one class to acquire the properties and methods of another class. This principle promotes code reusability and hierarchical classification. The class that is inherited is known as the 'parent' or 'super' class, and the class that does the inheriting is known as the 'child' or 'sub' class. The child class can add its own methods and properties in addition to those inherited from the parent class.

Polymorphism is a principle that allows one interface to be used for a general class of actions. It allows methods to behave differently based on the object that is calling them. This principle is often used to simplify code and improve its readability. For example, the same method name can be used in different classes, but the implementation and result can differ based on the class.

Abstraction is the principle of simplifying complex systems by modelling classes appropriate to the problem, and working at the most appropriate level of inheritance for a given aspect of the problem. It involves creating simple, abstract models of more complex, real-world objects and systems. This principle helps in reducing complexity and increasing efficiency by allowing programmers to focus on the essential features of the object.

In summary, these four principles of OOP provide a clear structure for organising complex programs. They allow for code to be easily modified, extended, and maintained, making OOP a popular programming paradigm.