Though at the rate we're going, we'll probably soon see it in a dictionary. In which case it would then start to make sense to basically include all random two letter combinations as possibly meaning something.
If you've ever spent any time looking around at blogs, blog comments, YouTube or YouTube comments, you've seen this one a million times by now. It has made you either confused (if English isn't your first language), slightly distressed (if it is, and you give a damn), or nonplussed (because you grew up with a cell/mobile phone, or with the mistaken perception that e.e. cummings had a right to determine the case of his initials).
Funny (no, I don't mean humorous) thing is, 15 years ago this was not a problem. For those of you who don't know, 15 years is not a long time. Particularly in terms of social change. As with everything that means something, the creators and controllers of the internet have found a way to make inaccuracies mainstream. So it goes with the English language and the use of "im".
What is "im" and what is correct?
I'll make this completely simple.
"im" is short for "instant message" which is either a noun (in the case of "send me an im"), or a verb ("im me"). Both of these are actually also incorrectly used at best.
The "abbreviation" "im" is also what people are writing instead of "I am". Some are also writing "i'm" uggh.
"I am" is the main expression of expressing the present or constant state of being in the first person in English...like "(yo) soy/estoy" in Spanish, "je suis" in French, and so on.
Notice that "I" is always capitalized (that means not "i").
An example of the correct usage of "I": I am (I'm) so hungry that I could eat a horse.
Notice that both instances of "I" are capitalized!!
So the next time you see "im sure that i have to...[bla-bla-bla]." Give that person a little something to think about.