Can you explain the principles underlying the SOLID approach in object-oriented programming?

SOLID is a set of five principles of object-oriented programming aimed at creating flexible, extendable, and maintainable systems:

• S (Single Responsibility Principle) — The class should have only one reason to change, meaning it should perform a single specific task.

• O (Open/Closed Principle) — Software entities should be open for extension but closed for modification.

• L (Liskov Substitution Principle) — Subtypes must be substitutable for their base types without altering the correctness of the program.

• I (Interface Segregation Principle) — It's better to have several specific interfaces than a single general-purpose interface.

• D (Dependency Inversion Principle) — High-level modules should not depend on low-level modules; both should depend on abstractions.

Applying these principles helps create code that is easier to test, extend, and maintain, reducing coupling and increasing modularity.