I have a new mission in life. Grammar Girl solidified it. I have to start putting one space after the end of a sentence and not two. This sucks. I haven't written a single sentence in this paragraph so far without doing it (I've corrected it each time). I've been hearing this in various places, but I never really followed it. I hadn't gotten enough of a consensus on whether it was proper or not.
Grammar Girl says that two spaces was the way cavemen wrote on their typewriters. They included two spaces because the fonts were monospaced, and they needed enough space to distinguish when a new sentence started. Otherwise the mammoths would get them. Now we don't need that because computers and the like, brought to us by those helpful aliens, make type easier to read and two spaces unnecessary. Although, personally, I prefer seeing two spaces after a period. Not just because it means I won't have to change, but it still makes things easier to read.
I've been taught to use two spaces after a sentence since I was a junior in high school, when I took keyboarding. It's served me well all through college, when two spaces added a little more length to my essays. Woe to the student who did not know this secret. So basically, let's say about eleven years of using two spaces and never being told otherwise. Flash to where I'm trying to get stories published and the slightest mistake could cost me a place.
What this does do is give me a better reason to scan Black Hole Son for punctuation and formatting errors. Turn on formatting in Word and look through all the pretty dots. That will be quite an arduous task.
It's going to be a hard habit to break.