I always thought it was two until maybe a year ago. It was surprisingly easy to change.
First of all, I’m aware that two spaces for most screen editing gets reduced to one, so I’m talking about print editing or text which is NOT subject to HTML conventions.
Two spaces for proportional fonts looks perfect to me. One looks a little too scrunched. Of course, this is probably because that’s the way it has been for 30 years of digital editing, but I see no moral or artistic reason to change or worry about it in the slightest.
And I am the kind of editor who is annoyed by “extra” spaces where there shouldn’t be, like between words in a sentence or after a tab or bullet or other indentations. Those are glaringly wrong; I spot them frequently in printed material; I easily detect them and remove them when I edit submissions from other sources. The two-space after a period does not hit my eye in the same way. Just to be consistent, I might even put one in.
Consistency might be one reason for all of these things. I am editing a newsletter right now with 15 articles from 12 writers. Most include phone numbers and they look like this: 213.255.1000, 213/255-1000, (213) 255-1000, and 255-1000. Some are bold, some are italic, some neither. But all of them will look the same after I’m finished. Consistency.
Don’t fight them, and don’t turn them off. Green Squiggly Lines are your friends. They’re telling you that something may need your attention, and except for the stupid grammar suggestions, are worth fixing (double words, double spaces, extra returns, etc.).
One space!!!
I used to be a two-spacer. But I’ve seen the light and changed my ways.
When someone sends me something to edit, and there are two spaces after each period, I literally cannot read it. :mad: I globally replace each double space with one space before reading or editing.
As opposed to HTML, in word-processing programs it makes a difference which font is being used. Sometimes in Word I can’t visually tell the difference between one or two spaces, because of proportional setting.
Really, this isn’t what we should be griping about. We should be griping about people who use spaces for formating! I’m talking about people who type 5 spaces to indent, or 40 spaces in order to make the date in a letter appear centered. Then, when someone else comes along and alters the document later, everything gets misaligned, and the editor has to delete all the spaces to format the thing correctly.
To all you people who do that: If you can’t comprehend what’s wrong with this, then throw away your computer and go back to using a typewriter.
When I receive an article or letter, I run a macro which does the following:
- Change all multiple spaces to single spaces.
- Change all paragraphs in the document to have 8 points of space after them.
- Remove all spaces at the beginning of a paragraph.
- Remove all blank lines.
- Change all ’ symbols to apostrophes/typographer’s single quotes.
- Change all " symbols to typographer’s double quotes. *
- Change all instances of “. to .” and “, to ,”
- Change all instances of – to em dash
Then I take a manual pass fixing things like misused degree symbols, making phone numbers fit the style guide, and looking for goofed-up parentheses, ellipses, dashes, and such.
Then it’s ready to edit for content. 
** I do have to manually check for places where the " symbol was used to mean “inches,” and change it back.*
I’ve been using a single space for many years now.
Though I must admit that I’ve never understood the reasoning of ‘with fixed-width, you have REALLY WIDE spaces, and you should use two. With proportional-width, you have very narrow spaces, and you should only use one.’
Doesn’t that seem intuitively backwards? 
How can something so simple and slight drive you nuts? This is what I don’t understand. I try to remember it’s the thing now, but I typed with two spaces for nearly 30 years before this became fashionable. And I’m looking at posts on this very thread trying to discern the difference. I see nothing!
I mostly use two spaces out of habit. I learned on a manual typewriter back in the 60’s. And still used 2 spaces in the early 70’s on an IBM Executive typewriter–with proportional spacing. And, even later, when I used an IBM Selectric Composer for a hippie newspaper.
I promise I’ll clean up my act if I ever submit anything for publication.
I started using two spaces when I took a typing class in the 7th grade, and I still do so today. It just looks right to me, whether it’s a proportional font or not. I could switch if I had to, but why should I have to? Because it’s “wrong”? The fact that some quasi-authoritative text has declared it wrong is immaterial to me. Does it cause misunderstanding of the text? No. Can my audience grasp the message I’m trying to deliver? Yes. Is using two spaces a common enough practice that many people would argue it’s better than one? Yes. Accordingly, “wrong” is simply opinion, not fact.
I plan to continue using two spaces until my fingers are too old and decrepit to type, if for no other reason than to piss off Farhad Manjoo and his disciples. I can imagine few things more unpleasant than sitting at Thanksgiving dinner with that douchebag and being lectured on the proper way to typeset my writing. Fuck him.
Meh. We’ve done this many times. Two spaces is an archaic convention, automatically removed by some (not all) some applications, one of which is the current SDMB software.
The only thing “two spaces” have going is they make things much easier to read, even in proportional fonts.
Everyone I work with can spot a single space usage, even lost in the middle of page after page of dense, boring government text – they catch all cases where I miss that second space. So people saying “You can’t even see it/notice it” just mean they can’t see it. And I find it certainly does help by adding that tiny little bit of whitespace that helps visually separate logical the units we call sentences. (Generally, whitespace improves readability; I find this is one such case).
Other than that, no reason to recommend it.
I give up, how is your macro removing blank lines? I have written myself various macros, but I haven’t stumbled across anything that will reduce 2-3 blank lines to one (it’s easy to add them with a macro, but remove them?), which would be pretty damn useful with some of the stories I get.
I read the same article this morning. Learned two spaces in the 90s and it took all of a week to recondition myself to one space.
My approach:
On a computer where you are likely to be using a variably spaced font: 1 space.
On a typewriter where you are likely to be using a mono-spaced font: 2 spaces.
(Also on a computer with mono-space fonts)
On a side note, especially for all your two-spacers, note how many spaces occur in your posts. It’s one. HTML/Browsers doesn’t recognize extra white space and will reduce any number of spaces to one (unless you use the PRE tag). You’ve been reading SDMB, and most Internet-based things, with once space for the last decade or so. On the plus side, it means you don’t have to change your habits!
Yes, yes, a thousand times yes. Spaces used for formatting make my computer-assisted translation software cry.
I learned to type late in life, and picked up the “two spaces” habit while doing so. It’s not a huge deal to me- so slight, in fact, that I can’t even tell when anyone uses one space or two. As such, why would I change, if it doesn’t affect my career or life in any way? I honestly don’t even understand how it can bother anyone.
As an aside, pressing the Space Bar twice on the iPhone automatically types a period and one space- so there’s not even any real reason to break the habit there, either. The habit is just not a big deal, certainly not one I’m going to invest any effort into changing. And for those who say that typing the extra space is just wasted effort: typing two spaces doesn’t slow me down in any way.
This post has sentences with both one space and two spaces. Looking back, I can only see the difference if I know it’s there and I’m actively looking for it. Again, no big deal, so I’ll just keep using the one I’m used to, thanks.
I’m a one-spacer because it never occurred to me to use two. I have no office skills, though, so I don’t know another way to indent.
You are my hero.
I have tears in my eyes over the beauty of your macro.
I wish I knew how to create such a macro. 
If you are seeing a difference, you are imagining it. As has been pointed out, HMTL will only show a single space even if you type in two (or more). There are actually ten spaces between this sentence and the previous one.
But not when you’re typing it in (in the text entry box), only once you submit it. As a matter of fact, I can now easily see the ten spaces in your post as I’m responding to it.
Meh. I learned to type on a manual typewriter in the 1970’s which, no doubt, accounts for my two-space habit. Sorry for being an old fogey, but if you live long enough it happens.
Personally, it matters little or nothing to me. If I’m working on something and the style convention is announced “one space after the period” I can adapt, but ya know, on the privacy of my own computer, how I do it is my business. (And editing to conform to the requirements of business or commerce is likewise my responsibility). No doubt because I was “raised” on two spaces I like the way it looks, but I’m not going to get upset if the world changed when I wasn’t looking.
And yes, I used a rotary phone at home into the late 1990’s. Good lord, my sewing machine is treadle powered! Old fashioned is no problem in my house.
Like I said, though - if business requires it, I can easily adapt.