After my previous rant on the possessive its, I was pleased to discover
that the fortune program served up the following, earlier today.
It's is not, it isn't ain't, and it's it's, not its, if you mean it
is. If you don't, it's its. Then too, it's hers. It isn't her's. It
isn't our's either. It's ours, and likewise yours and theirs.
-- Oxford University Press, Edpress News