The possessive case shows ownership. With the addition of ’s (or sometimes just the apostrophe), a noun can change from a simple person, place, or thing to a person, place, or thing that owns something. There are a few different ways to form the possessive of a noun. We’ll discuss these ways below.
Do we add another s for the possessive form of a name ending with s? Which is correct, Chris’s chair or Chris’ chair? James’s car or James’ car? Actually, both ways are correct. If a proper name ends with an s, you can add just the apostrophe or an apostrophe and an s. See the examples below for an illustration of this type of possessive noun.
But when you have a plural noun that ends in s, add just the apostrophe. This is also true when you have a proper noun that’s plural.
When you have an ordinary noun like student, you can tell whether the possessive form refers to one student or many students by looking at where the apostrophe is. When you’re talking about one student, add apostrophe + s:
In the sentence above, we are talking about the favorite subject of one student. When you’re talking about many students, add an apostrophe.
In the sentence above, we are talking about several students who all share the same favorite subject.
If you have a compound noun (for example, when you’re talking about two people who jointly own one thing), change only the last noun to the possessive. The examples below illustrate this usage of the possessive case.
If the possessor is a building, an object, or a piece of furniture, you don’t need to add an apostrophe to show possession. See the examples below for reference: