Who Is: Ariana Grande?

Guys, who is Ariana Grande? I see the name a lot and at this point I can pick out her face in a small crowd, but who is she? I'm pretty certain she is a singer, but from the memes I see, she is not a very good one. She did lick a donut and put it back and that was frowned upon by the world bc it was...un-American? Who is she dating? Is she just a shitty teenager with some good luck? Lets investigate.