Punctuation / A Primer of Information about the Marks of Punctuation and their Use Both Grammatically and Typographically

by Frederick W. Hamilton

Rules for the Use of the Apostrophe

1. The apostrophe for the possessive case is added only to nouns, not to the pronouns, which have their distinct possessive forms. Its is a possessive pronoun. It’s is an abbreviation for it is. Do not use an apostrophe with the possessive adjectives hers, ours, yours, theirs, its.

2. All nouns in the singular and all nouns in the plural except those ending in s take an apostrophe and s to form the possessive.

Nouns in the plural ending in s take an apostrophe only to form the possessive.

There is much difference of opinion as to the invariability of the rule concerning singular nouns in s. DeVinne advises following the pronunciation. Where the second s is not pronounced, as often happens, to avoid the prolonged hissing sound of another s, he recommends omitting it in print.

Moses’ hat, for Moses’s hat.

For conscience’ sake.

3. The apostrophe indicates the omission of letters in dialect, in familiar dialogue, and in poetry.

That’s ’ow ’tis.

’Twas ever thus.