In case we hadn’t beaten the apostrophe discussion to death, here’s an illustrated guide to proper usage from the guys over at TheOatmeal.com, a site full of quizzes and comics with (often misleadingly) clever titles.
It pretty much covers all apostrophal eventualities. One thing I’d like to add to the it(’)s question: think of the possessive “its” like “his” or “hers.” Those possessive pronouns don’t have apostrophes either. Neato!
Have grammar or punctuation quandaries of your own? You’re not alone. If you’re unsure, then others probably are, too. (Extensive market research of both this blog’s readers indicate that whoever you are, you’re most likely wicked smart.) Feel free to email the Unhappy Mediator with questions and maybe we can all learn something.
Meantime, click the apostrophe chart on the right, or visit the original at apostrophe.me
Happy punctuating.
ps. I second that –>
No Happy Medium 
A guy I went to elementary school uses apostrophes for every time he comes across an “s” at the end of a work (this is on facebook of course). Like: “Yes I am a Yankee’s fan, but my father loved the Phillie’s, so little hard to be happy right now”
However, I firmly believe that it’s != possessive is an error in our language that should be corrected, much like the lack of a plural for you (and the necessary creation of “y’all” and “yuns.” Your comparison to his and hers is persuasive, but counter intuitive language is helpful to no one.
Terry, I feel you. Often it’s as though the rules of the English language were created for the sole purpose of breaking them — and then calling it another rule.
The fundamental problem this late in the idiomatic game, however, is education in this country. (I’d be curious to see if apostrophes baffle the Brits as they do the Americans.)
It’s totally annoying when “rules” are counter-intuitive…
You use an apostrophe to show possession. Except when you don’t
…but for what it’s worth, the possessive form of “it” does more or less fall in line with the apostrophe-less possessives of the other pronouns. To wit:
my………….our
your………..your (plural. sigh.)
his/her……..their
People probably consider this reasoning obscure. It isn’t obscure (that is, it’s not arcane usage we’re talking about here); it’s just that our schools never bothered to teach us properly, so it seems like a lofty, academic consideration.
I can safely say that most of my initial grammar knowledge came from paying close attention in Spanish class.
What about people who can’t decide between using and not using apostrophes?