Jared Spool explains how changing one button in a site's checkout process increased sales by $300 million per year. (He doesn't name the retailer in the article, but it starts with "A" and ends with "mazon.com".)

This isn't surprising—even if a site's designer is trained in the specialized discipline of typography (which is unlikely), the person who actually marks up the content (or pastes it into the content management system) probably isn't. But the fact remains that poor typography is one of the most common and most easily avoided blemishes on the web.

Am I being pedantic? You may think so—but I encourage you to hear me out and give it a try. I think your pages will read more easily, and look more professional and consistent. Even if readers aren't consciously aware of the typographical subtleties, they do increase a text's ability to communicate—that's why the conventions were devised in the first place.

Rather than reinventing the wheel, I'll simply point you to A List Apart's excellent article on the subject, with a few addenda of my own:

• As the ALA article explains, a hyphen is not an em-dash or an en-dash. The hyphen is also not a minus sign—there's a separate glyph for that. It's −.

  Similarly, the lowercase letter x is not a multiplication symbol—that's ×.

  These glyphs are designed to align well with numerals and with each other. Here's the vernacular version:

  9 + 3 - 4 x 2

  And here's the correct version:

  9 + 3 − 4 × 2

  Which one looks best to you?

  (If you're looking for the division symbol, that's ÷.)

• When marking up vulgar fractions (i.e., those in which the numerator and denominator are separated by a diagonal line, as in "1⁄2"), use the fraction slash (⁄) rather than the regular slash.

• If you're using Windows, you can type exotic characters by holding down Alt and typing the character's four-digit code on the keypad. For example, Alt+0151 produces an em-dash.

• If you're marking up foreign words (or English words, for that matter) which contain diacritics (commonly known as "accent marks"), then include the diacritics! They aren't just there for decoration—they're part of the word's spelling, and if you get them wrong, you've misspelled the word as surely as if you'd substituted one letter for another. It's "jalapeño", not "jalapeno"; "sauté", not "saute"; "fête", not "fete".

Granted, useful content and a solid technical foundation are more critical to a site's success than proper use of em-dashes—but every whole is the sum of a thousand details, and good typographical habits will become second nature after a short while.