Robert C. Martin created the SOLID principle collection where “SOLID” is an acronym for the following principles:

• Single Responsibility Principle (SRP)
• Open-Closed Principle (OCP)
• Liskov Substitution Principle (LSP)
• Interface Segregation Principle (ISP)
• Dependency Inversion Principle (DIP)

This is the subset of Martin's principles that deals with the design of classes. For the full list of principles he collected see Robert C. Martin's Principle Collection.

• Robert C. Martin: Agile Software Development, Principles, Patterns, and Practices
• ButUncleBob: Principles of OOD

• SOLID