Last night, in our class on Usage and Writing, Zach brought up the ever-divisive question of whether there is one space or two between sentences. 

If you're anything like me, this is something you still think about all the time. In high school, my English teacher insisted we used two. A couple years later, an artsy friend of mine returned to our little rural campus after a semester at RISD, of all places, and told me there must only be one space, always. I quickly changed my ways. 

Then, in my first real office job, we had it beaten into us again that there were always two spaces, and so I've always just figured it's a matter of style, and perhaps a generational thing. 

But last night Zach gave us the full story, and the "right" answer (as right as most things involving usage can be) is to just use one space. 

Why is this? When the typewriter was invented, each letter was given the same amount of room, regardless of how wide it actually was. This is what's known as Monotype, and it leads to lots of space between each letter. In order to make it easier for the reader to tell where one sentence ended and another began, it became customary to put two spaces in between.

But hey, nowadays our fancy computers automatically kern things, putting the proper amount of space in between characters as you go along, to the point where two spaces just looks wrong. It's generally been decided by type designers and other tastemakers that you just shouldn't use two spaces. 

That said, if you really love two spaces, you can keep typing in Courier, which is still a Monotype font, or on an actual typewriter, and no one can argue with you. 

Further reading:

http://www.slate.com/articles/technology/technology/2011/01/space_invaders.html

http://lifehacker.com/5735680/an-argument-against-using-two-spaces-between-sentences