Typography.

Number One worst thing about the problem of old-school typers teaching new-school typers to still do the typewriter-era double-space-after-a-period:

ACK!! The extra space can spill to the next line and the wonderful justified margin is ruined! Ruined!

I thought I'd be clever and find text about this issue to illustrate the implications. The full text from the crop above is most enjoyable:

Modern proportional fonts have what's known as a "kerning table" that contains the optimum spacing for every possible combination of adjacent characters (including spaces). When authors create new fonts, they spend a lot of time compiling this information according to the actual shapes of their fonts' characters. When you stick in an extra space after a sentence, you defeat this wonderful capability the font's author worked so hard to include. But take heart: You've already made the far-more-challenging leap from typewriter to computer. (Well, I assume you have, if you're reading this.) Learning to drop that anachronistic extra keystroke is child's play by comparison. I know you can do it! –Ander

Well said Ander. As a professional typographer and type designer with over 35 years experience, I consider placing two spaces after periods to be an anachronistic typewriter convention perpetuated by high school teachers who don't know better. I suspect that the reason most people are taught to use two spaces in school is because their teachers were taught the same thing by their teachers (who probably used typewriters), who were taught by their teachers, and so on.

When personal computers finally brought real fonts and the capability to compose type to the masses, teachers and students who learned typing on typewriters failed to distinguish between the two. These people were suddenly introduced to real typography, but lacked training in the conventions associated with it. As a result double spaces, underlined text, double hyphens, straight quote marks, non-use of en and em dashes [another thing I love to see used appropriately! Or even used at all. En dashes and em dashes!! Woo hoo!], apostrophes instead of prime marks, poor kerning, inappropriate leading, three periods instead of an ellipsis glyph, and almost every other sign of bad typography became common.

Fortunately, this ignorance of standard typographic conventions has not spilled over into professional publishing. Pick up any magazine, book, newspaper or professionally published and edited material of any kind, and look for two spaces after the periods — you won't find them, they're not there, they don't exist. Professional typographers, designers, copy editors and printers just don't use use them and never have. In fact, they routinely remove them during the copy editing process in much the same way that errors in punctuation and grammar are corrected.

I'm (unfortunately) old enough to have caught the tail end of hot metal typesetting. In those days there was a style in use at some type houses of inserting a space and an additional "thin space" after a sentence. The use of this extra thin space wasn't common and was often dependent upon the font. I never remember an instance where someone thought it appropriate to put two spaces (or even a space and a half) after a period.

It's interesting that there are so many who lament the demise of the period followed by two spaces — not realizing that it is a convention that never existed, except in the old typewriter world. — Maylett 23:01, 20 August 2005 (UTC)