• Concept
• SOLID Principles

SOLID is an acronym that represents a set of five principles of object-oriented design that aim to improve code quality, making it easier to maintain and extend. The five principles are Single Responsibility Principle, Open-Closed Principle, Liskov Substitution Principle, Interface Segregation Principle, Dependency Inversion Principle.

A class should have only one responsibility. This means that each class should have only one reason to change and only one task or responsibility within the system.

A class should be open for extension but closed for modification. This means that the behavior of the class can be extended without modifying its original source code.

Subtypes should be substitutable for their base types. This means that derived classes should be able to be used anywhere their base classes are used.

A class should not be forced to implement interfaces and methods that are not used. This means that interfaces should be specific and cohesive, and classes should implement only the methods necessary for their operation.