It's this wee little thing called the ellipsis (...). Here's snippet I read on Wikipedia:
"The triple-dot punctuation mark is also called a suspension point, points of ellipsis, periods of ellipsis, or colloquially, dot-dot-dot."
Personally, I've never heard of any of these names, except for 'dot-dot-dot', which I reject on principle. I also personally reject the use of four dots. You have to stand for something...
While it may be true that only grammar nerds care what it's called, lots of people use 'em, and they can mean so many different things - here are a few fun uses:
The "suspenseful" ellipsis...
When you see this one, you're supposed to pause for a moment and wonder "Ooohhh... what's the afterthought trailing behind those little dots?" A period just wouldn't be appropriate here. Authors love to use this one.
The "stretch this sound out in your mind" ellipsis...
(See above "Ooohhh..."): Really hear that - ooooooohhhhhhh (it sounds like the 'oo' in goo and not the 'o' in poe).
Then there's the "ponder this" ellipsis...
Or, the "fill-in-the-blank" ellipsis, if you will. Those where right before they appear, you're given an ultimatum: "Would you rather..."
Never underestimate the "hesitation" ellipsis...
You're trying to give someone a hint without coming right out and saying what it is you want to say (I know you never do this, but bear with me here). Like, you're trying to end a conversation because you have something to do, but instead of saying "Hey, I gotta go," you say, "So, I'm about to run to the grocery..." and you wait. Hoping the other person will take that as a sign that you need to scram and not as a new topic of conversation. Oh yeah. You know what I'm talking about.
And I don't know if this next one really counts as an official usage of the lovely ellipsis. In fact, I'm not sure any of the ones I listed do, but oh well. Here's the last one - my favorite.
The "a hyphen just won't do here" ellipsis...
I use this all the time in emails. Sometimes I have two linked thoughts, but a hypen is just too abrupt, too jolting. There's supposed to be a sense of continuity, fluidity... you know, kind of like that. Like, I'm writing about something, and I'm ready to switch gears now, so anyways... oh yeah! Let me tell you about something else...
Kind of like that. And for those of you who weren't convinced before, now you know. I'm a nerd. And I don't mind. :)
(Note on picture at right: I decided to use this photo because it [along with the caption] is multi-dimensional. First note that there is, in fact, a National Punctuation Day. Fascinating. And there in the picture is its founder, who is really much hairier than he should be. But he does point out an interesting phenomenon - it's an epidemic even... why don't companies grammar check their signs?)
