This week I have two topics for you: The number of spaces after a period at the end of a sentence, and whether you should use "who" or "that" to refer to people (and pets).
Now here's our first listener question.
<His friends believe it is antiquated to use two spaces after a period at the end of a sentence.>
Yes, the caller is correct and he's also right that a lot of people haven't heard about the change.
Two Spaces After a Period? The Old Way
Here's the deal: Most typewriter fonts are what are called monospaced fonts. That means every character takes up the same amount of space. An "i" takes up as much space as an "m," for example. When using a monospaced font, where everything is the same width, it makes sense to type two spaces after a period at the end of a sentence to create a visual break. For that reason, people who learned to type on a typewriter were taught to put two spaces after a period at the end of a sentence.
One Space After a Period? The New Way
But when you're typing on a computer, most fonts are proportional fonts, which means that characters are different widths. An "i" is more narrow than an "m," for example, and putting extra space between sentences doesn't do anything to improve readability.
Notice how in this example, the "i's" and "t" take up much less space in the proportional font than they do in the monospaced font.
[Since publishing this post, I have become aware of a long and fascinating piece that disputes the entire conventional wisdom about spaces after periods. If you're interested in the topic, I highly recommend you read the post: Why two spaces after a period isn't wrong (or, the lies typographers tell about history).