What is SOLID Principles of Object-oriented Programming?

The SOLID principles are a set of guidelines that were introduced by software engineer Robert C. Martin to help developers design maintainable and scalable object-oriented software. The SOLID principles are as follows:

Single Responsibility Principle (SRP): A class should have only one reason to change. This means that a class should have a single, well-defined responsibility, and that responsibility should be encapsulated by the class.