what is a interface in c# ?

Answer 1

You can think of interfaces as contracts. Basically an interface defines a set of behaviours which any component that implements it must provide fuctionality to those behaviours otherwise you'll get a compiler error because you broke the contract. Furthermore to understand the entire concept try tutorialspoint or stackoverflow.

Answer 2

An interface looks like a class, but has no implementation. The only thing it contains are declarations of events, indexers, methods and or properties. They’re great for putting together plug-n-play like architectures where components can be interchanged at will

Answer 3

Is it not the same as the interfaces in java?