Apostrophes for Simple Possessive Nouns

An apostrophe before an s is a signal, not decoration. The moment you read "the dog's leash," you know one dog owns the leash, before the sentence tells you anything else. That's the whole job of a possessive apostrophe: it marks ownership and tells you how many owners, right at the word itself.

For a singular noun, the rule stays constant: add apostrophe plus s, no exceptions for nouns that already end in s. "The witness" becomes "the witness's testimony." "The class" becomes "the class's project." A singular name works the same way: James becomes "James's bike." Writers sometimes stop at just the apostrophe for names ending in s, giving "James' bike," but at this level the standard form keeps both the apostrophe and the s. The sound feels awkward, but the rule doesn't bend for pronunciation.

This topic sits right next to plural possessives and contractions, and the test leans on that overlap. A senator's aide, with the apostrophe before the s, means one senator. The senators' aide would mean more than one. Since apostrophe placement is often the only difference between singular and plural ownership on the page, read every possessive as a mini-clue: find the owner, decide if there's one or many, then place the mark right after the owner, adding an s only when the base word doesn't already end the possessive form.