True, there are people out there who genuinely do not know the difference between the pronoun-verb contraction it’s and the possessive pronoun its.

But you and I, gentle reader, are not among them. When you or I substitute it’s for its, we’ve made a simple spelling mistake, and all we have to do is ask ourselves whether or not we mean “it is.”

I don’t have to teach you how to form contractions or possessives. You’ve known the basics since third grade. You’ve even mastered the trickier possessives like woman’s and women’s.

You might be tripped up by odd or disputed rules, like whether to put an apostrophe in “six years’ experience” (yes) or to add another s along with the apostrophe to a singular name that ends in s like Archimedes (check your style guide, but most say Archimedes’s).

Still, if you’re like many of my readers, you’re interested in apostrophes. Maybe other people’s errors drive you nuts. Or maybe you like to gloat, just a little.

So here you go:

I just love these signs! The apostrophe that doesn’t belong is a perfect example of what Lynne Truss calls “the greengrocers’ apostrophe”—think “carrot’s 79 cents” or, my favorite, “potatoe’s.”

In the second sign, which includes a true possessive, no apostrophe is there to help us distinguish the owner of the car from a bunch of plural owners running around out there somewhere.

(For good measure, the first sign also offers Random Capitalization. I really love these signs.)

I’m almost afraid to ask. Want to share your favorite apostrophe howler? You know you have one.