The book that I’m currently reading is chock-full of some of my biggest typographical pet peeves.

Am I the only person who  notices when an extra space is used inadvertently between two words of a sentence? Even the grammar checker in Microsoft Word is kind enough to let you know when you make this mistake. It really drives me crazy; I seem to find doubled spaces everywhere I look. (Did you notice the doubled space in the first sentence of this paragraph?)

Speaking of doubled spaces, please don’t type two spaces after the closing period of a sentence. The Elements of Typographic Style (and Bill Hill!) back me up on this one. I know that your typing teacher told you to use two spaces. I don’t doubt that typing teachers are still teaching two spaces, but that doesn’t change the fact that it’s wrong. (Don’t use two spaces after a colon, either.)

One more – when typesetting source code with a fixed-width font, please don’t use ligatures. (Notice the “fi” – that should be fixed-width font.) I don’t understand why any fixed-width font would support ligatures anyway – doesn’t that violate the idea of letters being a fixed width? Of course, the easiest way around this problem is to stop using fixed-width fonts for source code – it reads a lot better in a normal font, anyway. On screen, 10pt Verdana is the best font for reading and editing source code that I’ve found; I’m sure a similar font would look great in print.

Update: David (a coworker) reminds me that there are books in print that use variable-width fonts for source code, most notably The C++ Programming Language (3rd Edition) by Bjarne Stroustrup, which uses an italic roman font, and Effective C++ (3rd Edition) by Scott Meyers, which uses a sans-serif font like Verdana. I found both to be more readable than the standard fixed-width Courier, particularly the latter.

Update 2: Speaking of source code, don't let your word processor or typesetting software make any helpful character substitutions. For example, I don't know of any programming languages that allow “smart quotes” around "string literals".

Update 3: Al prefers double spaces after full stops and colons, and asked that I quote the relevant passage from The Elements of Typographic Style:

2.1.4  Use a single word space between sentences.

In the nineteenth century, which was a dark and inflationary age in typography and type design, many compositors were encouraged to stuff extra space between sentences. Generations of twentieth-century typists were then taught to do the same, by hitting the spacebar twice after every period. Your typing as well as your typesetting will benefit from unlearning this quaint Victorian habit. As a general rule, no more than a single space is required after a period, a colon or any other mark of punctuation. [...]