The rules about forming possessive nouns probably cause the most apostrophe confusion. They vary a bit, depending on what type of noun you are making into a possessive. Here are the rules of thumb: For most singular nouns, add -’s: The dog’s leash The writer’s desk The planet’s atmosphere For most plural nouns, add only an apostrophe:

Apostrophes are used to show possession. For singular nouns and irregular plurals (those not ending in s), you should add ’s to the end of the word. For plural nouns ending in s, you should add only an apostrophe: the cat’s meow the people’s choice an old wives’ tale

To show possession using an apostrophe, add ’s for individuals (“Smith’s car”) and just the apostrophe after the s for plurals (“the Smiths’ car,” “the Martinezes’ dog”). By convention, names from classical mythology and the Bible ending in s show possession with the apostrophe only (“Jesus’ teachings”).

Apostrophes do the following: Show possession (i.e., The car that belongs to Michael = Michael’s car) Indicate the omission of letters in words when forming contractions (i.e., It is = it’s) Create plurals ONLY when showing the plural form of a lower case letter (i.e., be sure to dot your i’s)