Mark Williams - ... OMG stands for “Oh my God” or “Oh my goodness” or gosh, according to the OED. LOL stands for “laughing out loud”. It is used to describe ones reaction to a statement, picture of video.
The makers of the dictionary say the expressions are associated with the “language of electronic communications”. They are commonly used on forums, in emails, Tweets and text messages. Users may also see them on blogs and in Facebook entries.
The dictionary previously inserted IMHO, BFF and TMI into their publication. IMHO stands for “In my humble opinion”. Many users have shorted it to IMO – in my opinion – especially if they don’t feel their opinion is “humble” LOL.
BFF stands for “Best Friends Forever” and TMI stands for “Too much information”. TMI is commonly used when some describes bodily functions or explicit acts.
The OED says that the words are typically not spoken, but they are written. “in print, and even in spoken use… where there often seems to be a bit more than simple abbreviation going on,” their statement read.
via OMG and LOL make it in the Oxford English Dictionary | Digital News Report.