You’re putting together holiday cards or inviting friends and family to a year-end gathering. You’ve got festive music on the radio, the scent of gingerbread is wafting through the house, and you’re sipping a caffeinated concoction in a red cup. What the heck does grammar have to do with that?

As it turns out, quite a lot?and it’s all in a name. Your name.

One of the most commonly confused distinctions is among plural, possessive, and plural possessive versions of surnames, and errors are so frequent that it’s hard to recognize the correct form when you do see it. This week we’ll sort out how to get your name right?just in time for the holidays.

Plural: Surname + s

If you remember nothing else, remember this: there is no apostrophe in the plural, regardless of whether the surname ends in s, z, or y.

The regular plural is always formed by adding an s to the surname?no apostrophe. And unless the surname already ends in s, it doesn’t matter how you’d normally form the plural?it’s “the Freys,” never “the Fries.” Even if the surname is identical to a common noun (not a name) that forms an irregular plural, you still just add an s. You’re visiting “the Leafs,” not “the Leaves.”

Example A (incorrect): The Frey’s will be home next week. This is the possessive singular form?plurals don’t take apostrophes.

Example A (correct): The Freys will be home next week.

If the surname already ends in s or z, add ?es. Don’t add an apostrophe! It’s “the Joneses,” not “the Jones’s” or “the Jones” (the latter could only be the case if the surname was “Jone”).

Example B (incorrect): The Hess’s will be home next week.

Possessive: Enter the Apostrophe

To form the singular possessive of a surname, the general rule is to add an apostrophe + s as you would with a common noun?so it’d be “Christina M. Frey’s column” (see this Toolbox article for exceptions to the general rule). But note that adding the apostrophe + s only applies to a single surname, not a surname group like a couple or family. “Frey’s” refers to one Frey, not several.

To form the possessive of a group surname, add an apostrophe to the plural form. It’s really that simple.

Example C (incorrect): The Jefferson’s party will be next week. This is the singular possessive form, so unless there’s only one Jefferson and they go by “The Jefferson,” it’s incorrect. If the Jeffersons?more than one?are holding the party, use the plural possessive instead.

Example C (correct): The Jeffersons’ party will be next week.

To keep them straight, a quick review:

Plural: Add –s or -es. The Trumans are having a party. So are the Joneses.

Possessive: Add an apostrophe + s (general rule). Sarah Truman’s party was fun last year.

Plural possessive: Add an apostrophe to the plural form. The Trumans’ party [the party held by the Trumans] takes place the day before the Joneses’ party.

That’s a lot of partying?happy holidays!

Christina M. Frey is a book editor, literary coach, and lover of great writing. For more tips and techniques for your toolbox, follow her on Twitter (@turntopage2) or visit her blog.