Those pesky pronouns - possessives

For a relatively small group among the parts of speech in English, pronouns cause a great deal of difficulty for writers. The nouns which pronouns replace comprise a a large and ever-growing group. The number of pronouns, on the other hand, is small and static.

While forming noun possessives [discussed in last week's entry] may cause writers some problems, errors involving pronoun possessives are more frequent. The source of the confusion is the difference in how nouns and pronouns form possessives. Nouns use an apostrophe to form possessives, but apostrophes are mostly used with pronouns when forming contractions [an exception occurs in indefinite pronouns, such as anyone, everybody, something].

• With the exception of indefinite pronouns, pronouns do not use an apostrophe to form the possessive.
  

Unlike nouns in English, pronouns have specific forms to indicate their usage in a sentence, and that includes the possessive. Personal pronouns, interrogative pronouns [who, whom, whose, which, what], and relative pronouns [who, whom, whose, which, that] have one form when used as a subject in a sentence, another form when used as an object, and a special form for the possessive.

• Possessive pronouns include:
  

Singular: my, mine, your, yours, his, her, hers, its, whose

Plural: our, ours, your, yours, their, theirs, whose

Among these, the ones which cause the most confusion are its and whose. The writer using these pronouns needs to stop and think what the words means in the sentence.

its means "belonging to it"
it's is the contraction which means "it is"
whose means "belonging to whom"
who's is the contraction meaning "who is"

In Brief: Never use an apostrophe to indicate the possessive form of personal, reflexive, or relative pronouns.