Can you explain the main principles underlying SOLID and how they influence system design?

SOLID is a set of five principles of object-oriented design that help create flexible, extendable, and maintainable software systems:

• S (Single Responsibility Principle) — the principle that a class should have only one reason to change, meaning it should be responsible for a single specific task.

• O (Open/Closed Principle) — the principle that software entities should be open for extension but closed for modification.

• L (Liskov Substitution Principle) — Barbara Liskov's principle that objects of subclasses should be interchangeable with objects of the base class without affecting the correctness of the program.

• I (Interface Segregation Principle) — the principle that it is better to have several specific interfaces than a single general-purpose interface.

• D (Dependency Inversion Principle) — the principle that high-level modules should not depend on low-level modules; both should depend on abstractions.

Applying these principles promotes the creation of code that is easier to test, extend, and maintain, reducing the risk of errors during changes and improving system architecture.