POSSESSIVES

How is a possessive of a noun formed?

Noun possessives are generally formed by adding an apostrophe and an s:

a woman's prerogative

the dog's collar

the company's policies

Frank's comments

How is the possessive of a noun ending in s indicated?

For nouns ending in s (whether singular or plural), the possessive form requires only an apostrophe:

Unisys' annual report

Phyliss' comments

your boss' agenda

the actress' role

Is an apostrophe used in the possessive forms of pronouns?

The possessive forms of personal pronouns‚ my/mine, your/yours, his, her/hers, its, our/ours, their/theirs‚ and the relative pronoun who do not require an apostrophe:

John took my pencil. He knew it was mine.

Your account is overdrawn. Is this deposit slip yours?

His suit looked wrinkled.  The fault was his.

She had her own agenda. Your function was hers to define.

What do we know about its current status? 

Our bid is the lowest. Shouldn't ours be the one selected?

In their minds, the samples were theirs for the taking.

Everyone who came into the room this morning had a coat.

Whose coat is this?

By contrast, possessive forms of indefinite pronouns require apostrophes:

anybody's responsibility

someone else's worry

left to one's own devices

each other's concerns

May a possessive be used without a following noun?

Yes, this is a common occurrence:

Her agility resembled a cat's. 

How long will it be until we arrive at Fred's? 

Are you going to the doctor's? 

IBM's approach is solid, but I like Mac's better.