Spelling: Possessive Nouns
An apostrophe + -s ('s) marks the possessive form of any noun that hasn't already added a final -s to make a plural.
A possessive form of a noun is used to show ownership.
The children's room is large enough for all three of their beds and the dog's cushion, too. (The room belongs to the children, and the cushion belongs to the dog.)
The manager's strategy was to figure out the company's plan. (The strategy belongs to the manager, and the plan belongs to the company.)
Notice that the 's goes with the owner (in the examples above, children, dog, manager, and company). The possessive form is followed by the thing owned (in the examples above, room, cushion, strategy, and plan).
An apostrophe (') alone marks the possessive form of any plural noun ending in -s.
On the night shift, we fill several hours' time in front of the TV letting all those detective shows' suspense keep us awake.
In the sentence above, the possessive forms replace phrases which would have included of + a plural noun: the time of several hours, the suspense of those detective shows. Since hours and shows have already received an added -s when they became plural, they add only apostrophes now.
Most -s endings do not include apostrophes.
Amanda's son claims that she's watched all the midnight shows for two years. He thinks that's probably a record, even among those crazy friends of yours.
An apostrophe with a final -s marks either a possessive noun or a contracted verb. Do not use apostrophes with any other -s endings.
- Amanda's is a possessive noun, so it includes an apostrophe.
- claims, thinks are third person singular present tense verbs, so they need no apostrophe.
- she's is a contraction of she and has, so it includes an apostrophe.
- years, friends, shows are plural nouns, so they need no apostrophe.
- That's is a contraction of that and is, so it includes an apostrophe.
- yours is a possessive pronoun, not a possessive noun, so it needs no apostrophe.