The possessive case of a noun is used to show ownership ( Jordan's car, my sister's house) or other close relationship ( the president's friends, the university's position).
Problems with possessives
Sometimes possessives can cause problems. Do I add an ’s or just an apostrophe? Follow this rule: For singular nouns, add ’s, even if the noun ends in an ‐s or ‐z sound: dog's, house's, Wes's, Jesus's, Denver's, Keats's.
For most plural possessive nouns, add an apostrophe alone: several months' bills, many Romanians' apartments, the encyclopedias' differences. If a plural noun doesn't end in ‐s, add ‐'s, just as you would with a singular noun: women's issues, mice's tails.
Switching to an of construction
When a possessive noun sounds awkward, reword to use an of construction. This is a better way to indicate the relationship, especially when referring to an inanimate object: the top of the page instead of the page's top; the lawn of the building on the corner instead of the building on the corner's lawn; the main characters of Pride and Prejudice instead of Pride and Prejudice's main characters; the novels of Dickens instead of Dickens's novels.
Joint ownership
One last word about possessive nouns: When you are indicating joint ownership, use the possessive form in the final name only, such as Abbott and Costello's movies; Tom and Dawn's dinner party; Smith, Wilson, and Nelson's partnership.