a.k.a. abbreviations, acronyms, cyberslang, initialisms, leetspeak, online jargon, shorthand, SMS code, textese, text speak

With hundreds of millions of people texting daily, it's no wonder you've seen this cryptic looking code by now. Commonly used wherever people get online -- including IMing, SMSing, cell phones, websites, games, newsgroup postings, in chat rooms, on blogs, or on social media -- these abbreviations are used by people around the world to communicate with each other. NetLingo is also tracking a global list of worldwide text terms and international online jargon!

Acronyms have always been an integral part of computer culture, and they have since spawned a new language on the Internet. Commonly thought of as a series of letters that make up a 'word' there is a distinction between acronyms and shorthand.
The actual definition of an acronym and text shorthand is here.