A possessive noun is a classification of noun -- traditionally, a person, place, thing or idea -- that refers to the noun’s particular relationship to another noun. Rather than standing alone as a noun unit -- a subject or object, for example -- a possessive noun is usually part of a larger noun phrase.
Ownership and Possessive Nouns
Possessive nouns -- often formed by adding an apostrophe followed by an "s" to the end a word -- most commonly illustrate ownership. For example, in “Jenny’s shoes were left by the door,” the possessive “Jenny’s” reveals that the shoes belong to Jenny. Similarly, possessive nouns also demonstrate association, or relationship. For example,“ The company’s CEO retired yesterday.” Technically, the CEO does not belong to the company; rather, he is associated with the company.
Other Uses of Possessive Nouns
Not limited merely to ownership and association, possessive nouns may express origin, description or a value of time. For example, “the President’s policies” reveal where the policies originated. The phrase “today’s sales” uses the possessive “today’s” to describe “sales.” To denote a value of time, “year’s” could be used to modify “salary,” as in “a year’s salary.”
Forming Possessive Nouns
Not all possessive nouns follow the apostrophe "s" convention. For example, "it's" with the apostrophe is the contraction for "it is," while "its" without an apostrophe is the possessive form. Proper nouns -- plural or singular -- like "Smiths" typically receive an apostrophe "s" to form the possessive. Common nouns already ending with an "s," however, usually receive an apostrophe only. For example, "girls" would be written as "girls'."