Storytime...

Once upon a time, English was even more complicated than it is now.  Old English had four cases, at least four different kinds of nouns, and a number of inflexions (standard endings) to indicate the functions of words. The genitive case indicated possession and was spelled “es” for strong masculine nouns. So “the king’s gold” was “cyninges gold.” (If you’re interested in learning more about Old English and how much it differs from modern English, click here.)

Today, only two noun inflexions remain: “s” for plural and “apostrophe+ s” for possessive. That should be pretty simple, right?

Right.

The rules for apostrophe use

• Regularized nouns end with s to indicate plural. With the exception of numerals, letters, and symbols (e.g. the 1980's, learning your ABC's, too many $'s), plurals never take apostrophes. "SFU Athletics Needs Trainer’s this June” is WRONG. Try re-writing it correctly:
  • That's right, it should be written like this: "SFU Athletics Needs Trainers this June" (just a plural "s," no apostrophe needed) 
• Singular possessive nouns take ‘s.  If you can say – “of [noun]” then it is possessive. “The knights rusty old sword needs cleaning” should be “knight’s; the grammatical meaning is--"the rusty old sword OF the knight." The sword belongs to the knight. The knight possesses the sword. Hence, the apostrophe to indicate possession. 

TIP: It is correct to add an apostrophe + s to form the possessive of a singular noun ending in “s” or an “s” sound: the Jones’s new car, the glass’s fragility. 

• Plural possessive nouns are followed by an apostrophe only.  “All the knights’ horses ran away in the middle of the night.”  But note: “The children’s rocking horses seemed to move by themselves” (because “children” is an irregular plural).

• Contractions use an apostrophe to indicate omission. It’s always means it is. There is no such word as its’. 

Spotted in the wild: Examples of apostrophe misuse

• The “Grocer’s Apostrophe” (photos) 

• Mr. Rewrite: Greengrocer’s Apostrophe (video)

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Thanks to Amanda Goldrick-Jones, retired SLC Writing Services Coordinator, for generating this content for the grammar camp blog feature.