How to use an apostrophe

I see people using apostrophes wrong all the time, so I thought posting a link to this great Oatmeal comic would be helpful. I personally find the misuse of apostrophes annoying, although in some of the more complicated instances I can understand why.

It can be really embarassing if you get your apostrophe wrong, so mastering it will make you look like a writing pro!

Read the rest of this comic here.