What is SOLID Principles?
Five design principles for writing maintainable, flexible object-oriented code: Single Responsibility, Open-Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion.
S: Single Responsibility — a class should have one reason to change. O: Open-Closed — open for extension, closed for modification. L: Liskov Substitution — subtypes must be substitutable for their base types. I: Interface Segregation — prefer small, focused interfaces. D: Dependency Inversion — depend on abstractions, not concretions.
SOLID principles reduce coupling, increase cohesion, and make code easier to test, maintain, and extend. They are the foundation of clean object-oriented design and are relevant across all OOP languages.
