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The five SOLID principles are as follows:
Single Responsibility Principle states that classes should change for one reason. Thus, a class should have one duty. Multiple responsibilities make a class difficult to manage and test. Splitting the class into smaller, responsible classes is best. However, interface or abstract class is usually called single responsibility principle.
A class should be open for extension but closed for modification, when new requirements are generated under the Open/Closed Principle. In other words, we should be able to extend class behaviour without changing it. This is possible with inheritance and interfaces.
Liskov Substitution Principle staes that superclass objects can be replaced by subclass objects without compromising program correctness. A subclass should be able to replace its superclass without any difficulties.
According to Interface Segregation Principle (ISP) we should break huge interfaces into smaller, more focused interfaces so clients just need to implement their desired methods.
Instead of concrete classes, classes should depend on interfaces or abstract classes. This loose couples/ decouples classes for simpler testing and maintenance.