Most people are familiar with ASAP (as soon as possible), FYI (for your information) but there are many many acronyms out there. Each particular area has its own. My advice is don’t use them unless you are in an online forum of some kind (message board, game, chat). And if you see one cropping up often, look it up on one of the many online dictionaries available, such as Netlingo
The ones I see mostly are
AFAIK – as far as I know
FWIW – for what it’s worth
LOL – laughing out loud
BRB – be right back
LMAO – laughing my ass off
ROFL – Rolling on the floor laughing
HTH – hope this helps
BTW – by the way
W/C – week commencing
FOC – free of charge
IMO – in my opinion
IMHO – in my humble opinion
OMG – oh my god
TGIF – thank God it’s Friday
