I see it everywhere, not only in emails and blogs, but also in professional publications. It's driving me crazy with its ubiquity.
It's very simple. I don't know why it's and its give writers so much trouble. Well, check that, I do know most of the reason -- it's because when we want to make a word possessive, we usually add an apostrophe before adding the final S "That book is John's." "I'm going to Grandma's house."
But IT in the possessive does not add the apostrophe. "The car went its fastest." "The school raised its scores." Possessive IT - NO apostrophe.
IT'S is only for contractions. That is, turning two words into one. It is = It's. "It's a crying shame." ... It has = It's. "It's always been that way."
So, if you mean something that belongs to IT, use ITS. If you mean IT Is or IT Has -- if you can say what you mean using those two word combinations -- use IT'S.
It's beautiful in its simplicity.
