Better Know a Meme: TL;DR

Welcome to part two of my series, "Better Know a Meme".  This time, it's the Fightin' TL;DR!

     TL;DR, or as i is more commonly written, tl;dr, stands for "Too Long; Didn't Read".  This is used for two different purposes, one of which is extremely helpful and another which could drive me into a murderous rage.  The latter of these is when a user begins his message with tl;dr (at this point it would be prudent to mention that it is used most often on internet forums).  When used in this fashion, it is usually preceded by a well-written post detailing an argument extensively.  The poster of tl;dr often then rambles on about something only tangentially related to the above poster and uses vague and easily rebuffed arguments and often has no grasp of spelling or the basic rules of grammar.  It is often used to dismiss the previous poster's argument.
     The other usage of tl;dr is to summarize a person's post at the end.  A poster will write a medium-length or longer post (though sometimes I have seen posts of even one or two sentences summarized in this manner), then summarize it in a sentence or two.  The tl;dr is aimed at readers and would be more accurately be interpreted in this case as "If that was too long for you and you didn't read it:".  It's really helpful when a poster summarizes an especially long post in this way because the reader gets the gist of what the poster wants to say and if the reader is feeling lazy, only a quick scan of the post is required.
     And that's TL;DR!  Put it up on the big board, Jimmy!

tl;dr:  tl;dr stands for "Too Long; Didn't Read".