U or ur is text language. The correct form is "you are" or "you're"

Text messaging, or “texting” as most call it has developed a language of its own. Now even social network sites are full of incomprehensible messages, where people sending them assume everyone can understand them. Sometimes I have to search in Google to find the meanings... I just don't like it.

u and ur are Texting Abbreviations. u - you. ur - your/you’re For more general Texting Abbreviations. http://www.yourdictionary.com/grammar/abbreviations/texting-abbreviations.html :) :)

One should only use the abbreviations if there is really a limit of space (text messages) or time (online chat). If you have the space and time, then it's much better to write it out fully. So I agree with you; by putting shortened words where they're not needed is a quick way to look illiterate. ;)

well...those abbreviations are only used in"Chat"or"Text-messages",because this can really save your time to type,and funny,too...there are so many abbreviations indeed...let me give you some examples,like,TTYL-----talk to you later.................lmao=laugh my ass off(that is,it's very hilarious).. cuz=because....about='bout please=plz and so on...too many........and really has saved my time for typing..:D