SOLID stands for a set of fundamental principles in software design used to create maintainable, extensible, and flexible systems. SOLID is an acronym formed by the initial letters of these five principles:
S - Single Responsibility Principle
A class or module should have only one single responsibility. This helps in easier maintenance and modification of code without affecting other functionalities.
O - Open/Closed Principle
Code should be open for extension (adding new features) but closed for modification (not altering existing code). This encourages the use of inheritance, interfaces, or other extension mechanisms to add new features without modifying existing code.
L - Liskov Substitution Principle
Objects of a subclass must be substitutable for objects of the parent class without affecting the correctness of the program. This ensures that inheritance is implemented safely and correctly.
I - Interface Segregation Principle
It's better to have small and specific interfaces rather than a large interface with many methods. This helps avoid classes being forced to implement unnecessary methods.
D - Dependency Inversion Principle
High-level modules should not depend on low-level modules. Both should depend on abstractions. This principle encourages the use of dependency injection to reduce tight coupling between modules and make the system easier to test and extend.
SOLID principles enhance code structure, promote modularity, and reduce the risk associated with changes. These principles can be applied across various programming languages and development environments.