The apostrophe
Many writers (even good ones) mis-use the apostrophe. But you will find that editors appreciate articles with correctly used apostrophes. A few rules:
Rule 1
Use an apostrophe to show possession (owning). Put an apostrophe in front of the s to show possession by one person. For instance: the man's dog (one man owns one dog) Or, the man's dogs (one man owns more than one dog).
Rule 2
Use an apostrophe to show ownership by more than one person (or thing or other noun). But first make the noun plural. Put an apostrophe after the s to show ownership by more than one person.
For instance, all these are correct:
one dog's bone
two dogs' bones
one digger's spade
two diggers' spades
one cat's hat
two cats' hats
Rule 3
Use an apostrophe in contracted (shortened) words. An apostrophe is put in the spot where the letter or letters would be. For instance: ma'm (madam), don't (do not), we'll (we will).
Rule 4
To show singular possession with proper nouns ending in s or an s sound, today you must write the word and add apostrophe-s. Singular possession: Mr Jones's office, John Laws's car. Plural possession: the Joneses' house, the Lawses' cars.
Rule 5
Use an apostrophe and s after the second name only if two people possess the same item. For instance: Bill and Mary's car is now repaired. Bill's and Mary's cars are now repaired (separate ownership).
Rule 6
Don't use the apostrophe with the possessive pronouns such as his, hers, theirs, ours, yours. They already show possession, so do not need the apostrophe.
Rule 7
Using an apostrophe to show plurals of numbers, letters, and figures (two KFC's, 1700's) is today not used. Correct writing: She bought two CDs, he did best in the 1980s. Most mainstream Australian editors (and I) demand it without the apostrophe.