Internet slang is slang that Internet users have created and used, often in instant messaging and forum discussions. They are frequently acronyms, designed to save keystrokes in an attempt to speed up communication.
List of Internet slang
ROTFL: Rolling On The Floor Laughing
LOL: Laugh Out Loud
ATM: At The Moment
ASL: A request for Age, Sex, and Location.
BRB: Abbreviation for Be Right Back
IM: Abbreviation for Instant Messaging.
4: for, four