I'm gonna be honest. I've vaguely heard about vtubers before and I've seen some related memes like the subaru "hey ya" duck video on youtube but I really have no idea what vtubers are about. Can someone explain this to me?

Why do people like this? What's the appeal? I've been lead to believe there are different groups of vtubers, how does that work?
I can't think of any more questions but if you have other things to say that would shed light on it please go beyond my template. Thank you.