Image via Wikipedia
So, I have this addiction to Podcasts right now and I am always searching around for something new to listen to. While doing a search, I came across the Grammar Girls Quick and Dirty Tips podcast and uploaded as many free episodes as I could at that time. Pretty much every one of them, each only approximately five minutes long, have great tips and information that I have forgotten or wasn’t aware of. I just wanted to mention one today because I had typing class in high school and double spacing behind a period was drilled into my head and is a hard habit for me to break. Maybe a lot of you do not have this problem but at least I can introduce you to this wonderful podcast and helpful tips to grammar and writing.
Most typewriter fonts are called monospaced fonts. That means that every character takes up the same amount of space. It made sense using two spaces after a period because of the size of the letter and gave you that visual break that you needed. Now, no longer working on typewriters, most computer fonts are proportional fonts which means that letters are different widths. Single spacing is more logical. Chicago manual of style, the APA style book and the modern language association all recommend using just one space after a period.
Check out Grammar Girl Quick and Dirty Tips:
http://grammar.quickanddirtytips.com/
Check out the article on NPR News. At the bottom you will see a paragraph that explains the “rule” of spacing after a period.
http://www.npr.org/2011/11/03/141976518/the-war-between-google-amazon-facebook-apple?ps=cprs
Another good article is on About.com:
http://desktoppub.about.com/cs/typespacing/a/onetwospaces.htm
The Word Nerd 
I seriously didn’t realize there was a debate or that it had changed. And I just finished grad school, so I’m not sure my professors were aware or cared that much. It’s pretty embarrassing that I didn’t know this. In fact, I’ve been double-spacing this entire comment!