I have good news, you’re not wrong, no matter how many spaces after a period you use. Everyone thinks there is a right way and a wrong way, but in truth, like language it’s fluid.
When handwriting, we learned to put enough space after a period so we can see where the sentence ends. Remember using your pinky in grade school as a marker? When the Gutenberg press was introduced the spacing was set manually and printers made sure to do the same thing, they gave extra space at the end of sentences.
The story I was told, and learned from many sources is this: When the advent of the typewriter came about, everything changed. Because typewriters used monospace people needed to put two spaces after a period. When computers came about most programs and printers were monospaced, everything was designed to emulate a typewriter. Later developers made it so after a period one and a half spaces would be shown so people could stop pressing the space bar twice, it was more efficient and more accurate to how layout was done in traditional printing.
Problem is, that’s wrong! The article on Heraclitean River “Why two spaces after a period isn’t wrong (or, the lies typographers tell about history)” explains that the shift is not due to the typewriter, but due to publishers looking to save money on paper by removing extra spaces. They further say that this trend is only about 60 years old.
Regardless as to why the shift, generations have been trained to hit space twice after a period, it has become habit and even more, muscle memory. I learned to type on a typewriter, and then later a Commodore 128. Two spaces were still very much a thing and a necessity. I would not be able pass my level of Stickybear Thump without putting two spaces after the period, and any paper I turned in would be marked wrong by teachers. Now as a graphic designer and having worked in the print field for almost two decades I know that the industry standard isn’t two spaces, and what a printer expects. I’m a two spacer who understands that I don’t need two spaces anymore.
When laying things out for print my career has been filled with going through articles and reams of text, looking for the extra spaces, removing those extra spaces after a period so it is all uniform and works well. Most often the text I’m given has been written in Word. Word and other word processing programs have lovely shortcuts that automatically see two spaces and make them 1.5 and see one space and make it 1.5. Along with a bunch of other things where it corrects your typing. The problem is that when I import it into my layout programs to get it ready for a printer, all those formatting corrections come out as the raw typing (2 space=2.5, 1 space =1.5) and sometimes even ads even more spaces in. So I have to fix it.
There are many people who will tell you that two spaces is just plain wrong, and sometimes they will say it a bit harsher than they should. This article on Slate “Space Invaders” has some good points but the tone is judgmental and much of their history is wrong, or at least contested by other sources.
I much prefer Grammar Girl‘s article “How Many Spaces After A Period?” When it comes to grammar and rules, Mignon is the authority for me. Of course here it’s explained that both are right, depending on the situation. (more on that later)
One more thing to consider is that we have muscle memory of two spaces and developers have started taking advantage of it. Pull out your smartphone or tablet, start typing and at the end of a sentence tap the space bar twice, what happens? It puts a period and a space in for you, it formats it perfect for you. Today, most people use their phones more than their computer*. I believe that having this shortcut on smartphones is an indication that the split between typing one or two spaces is still divided and will be going back and forth for a few more generations to come.
Everyone wants to be right, so who is right? Well when typing in Word, it doesn’t matter. When laying out for print, it matters and you need to only have one space (which displays as 1.5). When typing a blog post, whatever you prefer is best. When writing a paper or something that requires you to abide by a stylesheet, go with that stylesheet. Chicago style says one space (now) and MLA says two. There are many more stylesheets to reference, so always check. When composing an email, check with your company’s stylesheet, if they don’t have one, then just be consistent. I know in the military it’s always two spaces, and they have their own reasons. For me, since I work in print, I go with one space, it saves my customers money and it’s the current trend. So my blog posts, emails, and everything I use one space. Or at least I try to, sometimes my muscle memory slips.
*A young marketing professional and I were talking recently about her phone and I asked if she backed it up to her computer, she laughed at me and said she didn’t own a computer. For me, that’s unfathomable, but it is the trend of the up and comers in industry and we must adapt