It seems that the debate about whether there should be one or two spaces after a period continues. There’s even a fairly entertaining video plus oodles of comments on the Microsoft site, at http://channel9.msdn.com/ShowPost.aspx?PostID=112. It’s a publishing industry standard to put a single space after a period at the end of a sentence. The publishing industry includes newspapers, magazines, books, and serious websites, like Microsoft’s own. This means that when you write for one of these entities, you need to comply with their industry standard, which also includes Chicago or AP Press styles, a House Style Sheet, and probably a template. When you are NOT writing for the publishing industry, like you’re doing your company’s technical documents or legal work or just internal documents that will not be published, you need to comply with the company’s standards. Your local editing or documentation department has a list of what those are. If there’s no standard set of rules, you can be a hero by establishing a House Style Sheet and making it available within your company. If you’re the person documenting styles, you get to say whether it’s one space or two. If you’re writing for academia, they don’t care about spaces because you are doing the publishing yourself. If you need to take up lots of extra space because your paper came up short, sure, go ahead and use the extra space. But don’t think your professors won’t cotton to it. It’s an old device, like triple spacing between lines and blank spaces between paragraphs. Like double spaces, a five-space indentation was standard for beginning a paragraph. Like double spaces, the indentation is also no longer an industry standard. You’ll find vestiges of the old indentation policy—the first default setting of tabs in Word is still at five spaces. Some publishers still use the indentation for the first paragraph of a book or an article, but all the rest are left justified. Don’t do this first indentation yourself, though. The publisher has a process for doing that automatically. I suspect that, like the double spaces, the ease with which word processors adapt to accommodate the font style has eliminated the need for the old indentation. With some publishers, you’ll find that they want a blank line between paragraphs, which would render the indentation needlessly wasteful of space. The bottom line, folks, is that it doesn’t really matter what you think is appropriate. It matters what the standards of your publisher are.