The goal is economy of style, accomplished, like most good writing, through vigorous editing. If you tweet, you know the drill: You've got a spot-on observation, deep thought or humorous nugget to get off your chest and onto the screen. You type away and you end up with, say, 220 characters. So you whittle, and you whittle some more. You work in a contraction or two. If you value the integrity of your writing, you avoid cute rhyme abbreviations ("Gr8!").