In the old days, those of us who took a typing class on a typewriter (mine was electric, at least) were always taught to type two spaces after a period. That was the proper way.
My mom was a typing style professional. She published a manual of typing style for the organization she worked for. She was (and still is) very particular about writing format and accuracy. She can't stand the ic's and u2's. She can spot the most hidden typos, spelling errors, word use mixups (it's vs its, there vs their), punctuations misuse, wrong spacing and indentations, etc. (Don't let her see this, she may find a few errors.)
As a result, I was excessively careful with the accuracy of my writing ever since I was in grade school. That's when I was learning English as a second language. Now that I've been speaking English on a daily basis for quite some time, I've changed. I actually make mistakes such as here vs hear, which would never happen to someone who learned how to spell before learning how to speak. Dreaming in English is probably a good indicator that you would start making those mistakes.
Anyway, back to the spacing topic. The new thing is one space in between sentences, not two. This was first brought to my attention by husband. So of course, we had a discussion about this. I was so sure that I was right. The truth is, we both are.
In the old days, we used monospaced font, that is, every letter or character occupied the same width of space. By putting two spaces between sentences makes the passage easier to read. (Courier is a monospaced font.) Nowadays, we use proportional typeface which contain glyphs of varying widths - that is, the letter "i" takes up less space then a "w". Some argue that the readability improves when using proportional typeface and therefore there is no need to put two spaces between sentences.
Did you notice I started this post using two spaces and then about half way through I switched to one space?
While I was doing some research on this subject, I was surprised to find that some people have really strong opinion about this.
What do you think? Are you a two-spacer too?