I don't know what XD means. What does it stand for?

Xtreme Diversiloquency

Just joking, I think it's meant to be a smiley face with squinty eyes like and

Ok, thanks so much!!!!!!

It's a face that people use as a substitute for ‘lol’ or ‘haha’, because it is supposed to represent someone laughing so hard at a joke, that they cannot keep their eyes open. The ‘D’ is self explanatory, it being the large smiling mouth.

Hope this helped!

Well it's basically a laughing emote. Try looking at ‘XD’ with your head rotated to the side and you should see.

It's easier to understand when it looks like this xD

Actually XD is a symbol for symbol and laughing mouth. Usually people use this symbol on social network or during chatting if something reallt funny happend.

Read more at sources:
http://slanghub.com/what-does-xd-mean/

It's supposed to mean “died laughing.”

Lol

I thought it meant Extreme Dude. Literally, for my whole life

turn your head 90 degrees to the left. XD

When funny things happend.