LOL

LOL, or lol, is an acronym for laugh(ing) out loud or lots of laughs, and a popular element of Internet slang. It was first used almost exclusively on Usenet, but has since become widespread in other forms of computer-mediated communication and even face-to-face communication. It is one of many initialisms for expressing bodily reactions, in particular laughter, as text, including initialisms for more emphatic expressions of laughter such as LMAO("laugh(ing) my ass off") and ROFL (or its older form ROTFL; "roll(ing) on the floor laughing"). Other unrelated expansions include the now mostly obsolete "lots of luck" or "lots of love" used in letter-writing.

The list of acronyms "grows by the month", and they are collected along with emoticons and smileys into folk dictionaries that are circulated informally amongst users of Usenet, IRC, and other forms of (textual) computer-mediated communication. These initialisms are controversial, and several authors recommend against their use, either in general or in specific contexts such as business communications.

How to use it?

Wrong way
(Meanwhile in "online chat"...)
Genpasaporte: My grandma just died :(
DarkerForce: OMG, LOL!
Genpasaporte: Why do you happy Dark?
DarkerForce: IDK, LOL?
Genpasaporte: Shouldn't you be sad?
DarkerForce: WHY, LOL?
Genpasaporte: nvm then, Bye :(
DarkerForce: Ok, lol?
Genpasaporte Block DarkerForce

Right way
Timvannn: Someone so stupid that someone had to call 411 to get the number for 911.
Yan_XU: LOL!
Timvannn: Ik,r?
Yan_XU: Yes Tru!