writing on IM can consist of...
shortning of words so that the proccess of typing is shortened...because seriously some people dont want to read paragraphs when there IMing
around 5 people at the same time!!
.........lol lmao lmfao jk wtf sn im aim omg omfg sXe hXc camfmofo ugh hey wassup wazzup haha lolz nvm nm w/e h/j b/j
....i think you get the point...........
also some people like to make the words look cooler by substituting letters for numbers or other letters, sometimes repeating a letter
(so be carefull when reading so you dont miss read somthing and make a disaster happer because of it)