The apostrophe

You should use an apostrophe to form the possessive case of a noun or to show that you have left out letters in a contraction. Note that you should not generally use contractions in formal writing. For example:

• The convertible’s engine has finally died. (the noun convertible’s is in the possessive case)
• I haven’t seen my project manager for two weeks. (the verb haven’t is a contraction of have not)

To form the possessive of a plural noun ending in s, simply place an apostrophe after the s.

• He has his three sons’ futures in mind.
• In many suburbs, the houses’ designs are very much alike.

Possessive pronouns—for example, hers, yours and theirs—do not take apostrophes. This is the case for the possessive pronoun its as well:

• The spaceship landed hard, damaging its radar receiver. (its is the possessive pronoun)

When you write it’s with an apostrophe, you are writing the contraction for it is or it has:

• It’s your accountant on the phone. (it’s is the contraction of it is)
• It’s been two years since I last visited you. (it’s is the contraction of it has)