Old Fashioned Rules With Which We Can No Longer Put Up
Ending a Sentence with a Preposition - OK!
In the past, I've been quite a stickler about the 'never end a sentence with a preposition' rule. Mainly for reasons of diagramming. But this editor provides a nice history of the rule, and her reasoning feels quite definitive. So if you haven't yet seen this video from 2011, watch it to learn why you can end a sentence with a preposition.
Double Spacing after a Period - NOT OK!
What you can't do, however, is double space after a period. Stop it. Not willing to take my word for it? Read the history (lots and lots of history) in Slate. Yes, Slate.
Language evolves. The technology of communication evolves. Let's evolve with it.