SOLID Principles

When consistently applied, SOLID principles ensure each class and interface has a precise, well-defined role, making changes manageable without breaking existing functionality. Applying SOLID transforms a fragile monolith into a modular system where new functionality can be added by creating new classes rather than modifying existing ones. SOLID principles are described as practical design tools, not abstract theory. The SOLID acronym stands for Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion. Violating SOLID principles results in code that is tightly coupled, hard to extend, and prone to cascading failures when any part is modified.