An Interface in C# Introduction Interface contains the method declarations. It can be implemented by more than one class. Multiple interfaces can be implemented by a single class. Method of a sub class overrides the method of an interface Output If the method of an interface is not overridden, then the following error comes. Error Message Multiple interfaces can be implemented by a single class Output Multiple Class can implement the same interface and can use it, according to their requirement Output Interface cannot contain the definition of a method. Error Message Conclusion Interface can be used in C# for multiple inheritance. This particular point will b covered in my next article.