The New Campus Fever: Yik Yak Anonymous App

What is this Yik Yak anonymous app and what makes college campuses go all rage it? is there any harm in using this?
23-year old graduates, Tyler Doll and Brooks Buffington, were the mastermind of this all. The app was released late 2013. But what really is this app? If you are familiar with...
The New Campus Fever: Yik Yak Anonymous App