Q: Over dinner, a friend said she had corrected a co-worker’s mistaken use of “its” where “it’s” was appropriate. She described this as a grammatical error, but our dinner party was evenly split over whether it was grammar or spelling. Any chance you can shed some light on this?

A: On a superficial level, this qualifies as both a punctuation error and a spelling error.

But on a deeper level, it’s a grammatical error, because it represents a failure to distinguish between (1) the possessive pronoun and (2) the contraction.

It also represents a failure to recognize that possessive pronouns don’t sport apostrophes.

So the problem is more than just a spelling goof in our opinion. That probably puts us into the grammar-error camp.

You might be interested in a blog entry we wrote last year about how the apostrophe came to be the mark of possession.

If any reader of the blog is confused by “its” and “it’s,” check out our 2007 posting about the “it” squad.

In the meantime, here’s an easy way to keep “its” and “it’s” straight: If you can substitute “it is” or “it has,” then “it’s” is right. Otherwise, choose “its.”

(The language blogger Jan Freeman argues that these “its”/“it’s” errors are merely typos, but comments from readers of our books, articles, and postings over the last 15 years suggest otherwise. Although a lot of the mistakes are undoubtedly typos, many, many people believe the presence of an apostrophe in “it’s” makes it a possessive. In fact, Pat’s first book, Woe Is I, was inspired by a publisher whose highly educated, adult children didn’t know the difference between these two words.)

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