07.27.13 by MJ My friend has asked this question one week ago. He was not able to understand the usage of interfaces in his small projects. I decided to explain it, but I knew that it would be a long journey, from the beginning to the end. FInally he got the idea. Today I will try to explain this to you, audience. “Q” is defined as a question. “A” as an answer. Q: What is interface? A: We can say that interface is a kind of class which has declarations of all methods, properties or events. I...