I've made no secret of my disdain for using two spaces after a period. What amazes me is how prevalent it is. It's been a year or two since typewriters were widely used and you'd think that would be more than enough time for this dinosaur to be laid to rest. Alas, 'tis not so. I made a crack about this on Facebook today after reading a coworker's report that somehow managed to put three spaces after a period. Lo and behold, Two Spacers jumped out claiming that they were correct.
I don't want to hurt any feelings here, but Two Spacers are wrong. Here is Grammar Girl with the skinny.
Although how many spaces you use is ultimately a style choice, using one space is by far the most widely accepted and logical style. The Chicago Manual of Style (1), the AP Stylebook (2), and the Modern Language Association (3) all recommend using one space after a period at the end of a sentence. Furthermore, page designers have written in begging me to encourage people to use one space because if you send them a document with two spaces after the periods, they have to go in and take all the extra spaces out.
Okay. Okay. It's a style choice, so feel free to use it if you must. Just don't be surprised if I'm editing your document and I do a find and replace to make all of the double spaces into single spaces.