Answer:   .Net uses the SOLID design principle which includes the following:
• Single responsibility principle (SRP)
• Open-Closed Principle (OCP)
• Liskov substitution principle (LSP)
• Interface segregation principle (ISP)
• Dependency inversion principle (DIP)

Answer:   SOLID principles are the design principles that are used in .NET. These principles provide us with ways to move from tightly coupled code and little encapsulation to the desired results of loosely coupled and encapsulated real needs of a business properly. SOLID is an acronym of the following principles -
S: Single Responsibility Principle (SRP)
O: Open closed Principle (OSP)
L: Liskov substitution Principle (LSP)
I: Interface Segregation Principle (ISP)
D: Dependency Inversion Principle (DIP)