used at the end of words to make them longer. instead of saying "It's taking too looooooonnnggggg." you would say, "It's taking too long~" Periods are rarely used after. Used by literates and occasionally preps.
can also be used as an exclamation point. originates from, well, the buttons being next to each other.
a laughing face, typically used by literates instead of lol.
to express more laughter, add d's. not used in a constant sequence, i.e. XDXDXDXDXDXD!!1 However, you can have two xD(D..)s in one sentence/IM response. can also add a semicolon (;) to express uneasyness or embarrassment.
Person 1: Okay. My brother just walked by with my mother bra as a jockstrap.
Person 2: xDXDXDXDXDXDXDX!!
Person 1: Okay. My brother just walked by with my mother's bra as a jockstrap.
Person 2: XDD Well, atleast SOMEONE's getting use out of them. XDD;;