It’s “its”, not “it’s”!
Grammarians (and editors) get all scholarly as they try to educate people about how to know the right form to use. They — all right, we — talk about things like possessives and pronouns and on and on. It almost becomes a matter of sitting down and making a detailed grammatical calculation every time the word “it” shows up in your writing somehow.
But it occurred to me a while ago that there’s a really simple trick for knowing when you’re supposed to use the apostrophe, and when you’re not. It’s almost deliciously easy, in fact.
So. What do you think the trick is?