SOLID is a set of principles for designing software that is easy to maintain and extend over time. The acronym stands for five principles: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion.
The Single Responsibility Principle (SRP) states that each class should have only one responsibility. This helps keep classes simple and focused on a specific task, making them easier to maintain and understand.
The Open/Closed Principle (OCP) states that classes should be open for extension but closed for modification. This means that you should be able to add new functionality to a class without having to modify its existing code.
The Liskov Substitution Principle (LSP) states that objects of a superclass should be able to be replaced with objects of a subclass without affecting the correctness of the program. In other words, subclasses should be able to be used in place of their superclasses without causing any problems.
The Interface Segregation Principle (ISP) states that clients should not be forced to depend on methods they do not use. This means that interfaces should be small and focused on a specific task.
The Dependency Inversion Principle (DIP) states that high-level modules should not depend on low-level modules. Instead, both should depend on abstractions. This allows for easier changes and flexibility in the system.
By following these principles, software designers can create code that is more maintainable, extensible, and easier to understand.