SOLID principles are a set of guidelines or best practices in object-oriented programming that help you design software that is easy to maintain, understand, and extend. These principles were introduced by Robert C. Martin (also known as Uncle Bob) and are acronymized as SOLID, with each letter representing a specific principle.

1. Single Responsibility Principle (SRP):
– A class should have only one reason to change and should have only one responsibility.
– A class that does too much violates this principle and becomes harder to test and maintain.

2. Open-Closed Principle (OCP):
– Software entities (classes, modules, functions, etc.) should be open for extension but closed for modification.
– The idea is that you should be able to add new functionality without modifying existing code.

3. Liskov Substitution Principle (LSP):
– Objects of a superclass should be able to be replaced with objects of its subclasses without affecting the correctness of the program.
– Subclasses must be substitutable for their base classes and should not change the behavior that clients expect.

4. Interface Segregation Principle (ISP):
– Clients should not be forced to depend on interfaces they do not use.
– Larger interfaces should be split into smaller and more specific ones to prevent clients from depending on methods they don’t need.

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.
– This principle encourages the use of interfaces and dependency injection to decouple components and make them easier to test and replace.

By following these SOLID principles, you can create code that is more modular, flexible, and easier to maintain and understand. These principles promote good design practices and help you write code that is easier to test, debug, and extend.