Originally Posted By: TheFallibleFiend
I learned the same thing. What changed it was not the Internet, per se, but the instantiation of proportional fonts.

http://en.wikipedia.org/wiki/Sentence_spacing
"With the introduction of proportional fonts in computers, double sentence spacing became obsolete.[13]"

... and later ...

"Most modern literature on typography says that double spacing is wrong,[18] but some non-typographical sources indicate that it could be used on a typewriter or with a monospaced font.[19]"


This rationale makes absolutely no sense to me. If the reason for double spacing between sentences was to make it easier to see that it was a space between sentences the fact that the double space in a monospaced font is greater than that in a proportional font would make it more critical to double space in a proportional font. The period would seem to be more easily lost in a proportional font since it takes up less space than it would in a monospaced font. It seems to me more like it is just the fashion in house style and for some reason has gained the status of inviolable rule.

Personally I find double spacing between sentences in proportional fonts much easier to read.