Explain Interface?

An interface is not a class. It is an entity that is explained by the word Interface. An interface has no implementation; it only has the signature or in other words, just the definition of the methods without the body. As one of the similarities to abstract class, it is a contract that is used to explain  hierarchies for all subclasses or it defines specific set of methods and their arguments. The main difference among them is that a class can execute more than one interface but can only inherit from one abstract class. Since C# doesn't support multiple inheritance, interfaces are used to execute multiple inheritance.