Could you list the main principles of object-oriented programming?

Basic principles of object-oriented programming (OOP):

1. Encapsulation — combining data and methods that operate on that data into a single object, hiding internal implementation details, and providing access through an interface.
2. Inheritance — creating new classes based on existing ones, allowing code reuse and extending functionality.
3. Polymorphism — the ability of objects of different classes to respond to the same messages (methods) in different ways.
4. Abstraction — highlighting essential characteristics of an object and hiding non-essential details.

These principles help create flexible, extendable, and maintainable programs.