I'm trying to explain something to one of my friends, and unfortunately, I'm not too good at that. Can someone help me explain (in a not-confusing way) WHY you put the comma in this sentence?

Question

[Millie, go get the papers off my desk.] or [What's wrong with you, you idiot?]

Thanks~!

Writeacher · Answer

http://grammar.ccc.commnet.edu/grammar/index2.htm
This is a magnificent place to find explanations of just about everything that has to do with grammar and usage. Bookmark it!!

Here's the webpage on comma uses:
http://grammar.ccc.commnet.edu/grammar/commas.htm
Scroll down and read the explanation and examples just above #5 -- you're looking for "addressed person's name."

Here's another; see Rule 4:
http://www.grammarbook.com/punctuation/commas.asp