What are the principles of SOLID in programming?

SOLID is a set of five design principles aimed at creating maintainable, extendable, and testable systems.

1. Single Responsibility Principle (SRP): A class should have only one reason to change, one responsibility.

2. Open/Closed Principle (OCP): Software entities (classes, modules, functions, etc.) should be open for extension but closed for modification.

3. Liskov Substitution Principle (LSP): Objects in a program should be replaceable with instances of their subtypes without affecting the correctness of the program. If class S is a subtype of T, then objects of type T may be replaced with objects of type S without changing any desirable properties of the program.

4. Interface Segregation Principle (ISP): Many client-specific interfaces are better than one general interface. Clients should not be forced to depend on interfaces they do not use.

5. Dependency Inversion Principle (DIP): High-level modules should not depend on low-level modules. Both should depend on abstractions. Abstractions should not depend on details. Details should depend on abstractions.

Applying SOLID helps create programs that:

• Are flexible.
• Are scalable.
• Are easier to test.
• Have lower coupling.