Quick quiz: When you type up something on your computer, do you add two spaces or just a single space after every period?
Some questions will always generate debate. The question of whether to place one space or two spaces after the end of a sentence ranks right up there with the question of over or under when hanging the toilet paper roll.
But just as there’s an unquestionable answer about toilet paper — it always goes over! — there’s also an answer for the spacing question.
People of a certain age will almost always gravitate toward placing two spaces after a period when they type. People of a different age insist there should only be one.
Who’s correct? Some feel it should depend solely on personal preference. But many style manuals insist there’s only one correct way.
The two spaces argument
In the age of typewriters, an age that ended before some of you were born, letters were monospaced. That meant they all took up the same amount of horizontal space on the page. To put it another way, both the letter W and the letter I, took up the same space from left to write in a word. So the W took the entire width of the character. The letter I had a gap between the letters to immediate left or right.
With that spacing, sentences could become a bit tougher to figure out. So conventional wisdom at that time determined adding an extra space between sentences would help the eye.
Thus the two spaces argument was born.
The Atlantic reported the results of a study that found using two spaces helped improve reading speed.
The single space argument
With the advent of word processing, computers could handle the placement of individual letters down to the individual pica. Word processors recognized what typewriters weren’t smart enough to know.
So spacing became automatic. Style manuals quickly adopted rules that relied on those word processors, thereby banning the double space practice. Just last year, Microsoft Word began flagging two spaces after a period as a misspelling.
Even the Associated Press Stylebook, which I largely rely on both professionally and here at this blog, insists that only one space is necessary.
In the  The Complete Manual of Typography, author James Felici writes the early history of typing was an exercise in inconsistency. But in the early 20th century, European typesetters began to settle on a single space and America followed soon after.
Most style manuals, including the Chicago Manual of Style, also advocate the single space. So if you follow a style manual, you may be obliged to follow its guidance…like it or not.
But even if you don’t follow a style manual, think about your manner of committing words to a page.
If you’re using a monospaced typewriter, by all means, use those two spaces. They will help the eye recognize the end of sentences.
But if you’re using a computer — whether writing up a report in Word or typing a quick email, trust the character kerning: go with the single space option. One space is really all you’ll ever need. Your eyes are smarter than you think!