'Fess up, Neatoramanauts. Who amongst you type two spaces after a period?
Well, according to Farhad Manjoo of Slate, you're wrong. Dead wrong:
What galls me about two-spacers isn't just their numbers. It's their certainty that they're right. Over Thanksgiving dinner last year, I asked people what they considered to be the "correct" number of spaces between sentences. The diners included doctors, computer programmers, and other highly accomplished professionals. Everyone—everyone!—said it was proper to use two spaces. Some people admitted to slipping sometimes and using a single space—but when writing something formal, they were always careful to use two. Others explained they mostly used a single space but felt guilty for violating the two-space "rule." Still others said they used two spaces all the time, and they were thrilled to be so proper. When I pointed out that they were doing it wrong—that, in fact, the correct way to end a sentence is with a period followed by a single, proud, beautiful space—the table balked. "Who says two spaces is wrong?" they wanted to know.
Typographers, that's who: Link