Did you know some punctuation “rules” are really only style choices? There are different styles of punctuation depending on what you are writing (e.g., manuscript, news story, legal document). The variations are minor but can be significant, especially to your editor. The punctuation guidelines listed here are geared toward novel-length fiction and non-fiction writing based on The Chicago Manual of Style.

Each type of punctuation has “rules” about what it does, where you should use it, when you should use it, why you should use it, and how to use it correctly.

Apostrophe
If you don’t want to deal with all the rules, there is another acceptable option. Please note this option doesn’t conform strictly to The Chicago Manual of Style, but it isn’t technically incorrect.

If the singular noun (before being possessive) ends in “s,” then only add an apostrophe; otherwise, add “s.” If the noun is plural, you never add the “s.”

Note: For words and numbers that begin with an apostrophe, if you are using “smart quotes,” the bottom of the quote should curl forward. Sometimes, with modern word processors, it is necessary to type a placeholder letter, then the apostrophe, then the desired number or letter to generate the correct symbol, and delete the placeholder letter.

Usage
1. Contractions

Example: It’s (it is), can’t (cannot), don’t (do not), won’t (will not), he’d (he would or he had)

2. Omitted numbers

Example: The class of ’77

3. Omitted letters (particularly slang)

Example: If it doesn’t kill ’em, it won’t hurt ’em.

4 To pluralize letters and words

Example 1: Are you enjoying the do’s and don’t’s of punctuation?
Example 2: Beth had 4 A’s and 2 B’s on her report card.

5. To show possession (The rules below are in accordance with The Chicago Manual of Style. The acceptable alternative (with some editors) was given above.)

5A. Nouns (singular): to show possession, add “‘s”

Example 1: Robert’s book
Example 2: My mom and dad’s car. (Only the last element of a noun unit takes the possessive case)

Exceptions (when to leave off the final “s”)

1. When the singular form of a noun ending in “s” looks like a plural and the plural form is the same as the singular, the possessive of both singular and plural is formed by the apostrophe only.
2. Add an apostrophe only when the last element of a name is a plural form ending in “s.”
3. Leave off the final “s” with names of two or more syllables that end in an “eez” sound (e.g. Euripedes).
4. Leave off the final “s” with names or words that end in a silent “s” (e.g., marquis).

5B. Nouns (plural): to show possession, add only an apostrophe (no “s”)

Example 1: The cows’ pasture. (multiple cows)
Example 2: The babies’ blankets. (multiple babies, multiple blankets)
Example 3: The Smiths’ home (The home of all the Smith family members)

6. Double possessives

Example 1: This is a portrait of Angela’s (Angela owns more than one portrait.)
Example 2: Melinda is a friend of Mark’s (Mark has more than one friend, and one friend is named Melinda.)

7. Idiomatic expressions/Genitive case

Example: For goodness’ sake, two weeks’ notice, a week’s worth, five days’ leave, hard day’s work