Yup, or you can think of the words "his" and "hers". We don't write "her's" or "his's", do we? But I see "it's" used instead of "its" all the time for some reason. I've even run into one person who put an apostrophe in front of every freaking 's'.
It was very difficult to read. Some people are just obsessed with the apostrophe. At one of the local Wal-mart customer service counters I saw a sign that said "NO RETURN'S ON BICYCLES". Well I guess we all know why the person who wrote that works at Wal-mart.
