Lloyd Borrett's Blog
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There is usually only one space after a period
I received a document from a friend the other day. Yet again I found two spaces after each period. It simply amazes me how this hangover from the typewriter age still persists.
Let me explain.
When a typewriter (the old-fashioned mechanical kind) types a letter, the carriage moves ahead by a set increment in preparation for typing the next letter. This increment is always the same. This means that typewriter typefaces have to be designed so that all the characters occupy the same amount of space on the line. These are so called "mono-spaced" typefaces.
In mechanical terms, you would say all of the letters of a mono-spaced typeface have the same "escapement," which is the distance the typewriter mechanism moves. In computer terms, you would say that they all have the same "character width." Creating mono-spaced typefaces calls for characters that have unnatural proportions. Wide characters can be squeezed, but narrow characters can only be designed to be so wide, so many of them (especially punctuation) have a lot of white space on either side of them.
The overall effect of this kind of typeface design is that the type you set using them looks very loosely spaced on the page. Thus, if you use only one word space at the end of a typewritten sentence, it's not wide enough to make an appreciable gap between one sentence and the one that follows it. This gap is a visual cue that you're transitioning from one sentence to the next, and if the space is too small, this cue just doesn't do its job.
More concisely put, double word spaces between typewritten sentences of mono-spaced typefaces help to make the type look more naturally spaced and enable it to be read more easily.
Thus in the days of the typewriter and fixed- or mono-spaced typefaces, people were taught to put two spaces after a period. Unfortunately, that teaching style seems to be still in the system, regardless that people are typically now using computers and proportionally spaced typefaces.
The typesetting systems used to produce books, magazines, newspapers etc. use proportionally spaced typefaces, where the width of each character can be customised to accommodate the natural shapes of the letters. For example, the width of the letter "i" is much smaller than the width of the letter "m". When this happens, type sets more tightly, which makes word spaces stand out more. A result is that one word space after a sentence is sufficient to provide that visual cue. Two spaces after a period simply look too wide.
Almost all books, magazines and newspapers are typeset with proportionally spaced typefaces. Pick up one and take a look. You'll see there is only one space after a period.
Today, when using computers, most of the typefaces available are proportionally spaced. Thus when using a word processor program, a desktop publishing program, a web page publishing program, e-mail program etc. with proportionally spaced typefaces, the correct solution is just one space after a period. Only when explicitly using a fixed- or mono-spaced typeface like Courier should two spaces be used.
So ultimately it's an issue of aesthetics and readability. The best solution on a typewriter with a mono-spaced typeface is two spaces between sentences, but on a computer when using a proportionally spaced typeface the best solution is just one space.
So if you were taught to put two spaces after a period, it's time to unlearn that habit. Now that you are aware of the issue and understand when to use two spaces and when to use one space, you will find that there is usually only one space after a period.