Using Apostrophes Correctly - A Primer

Apostrophes are used in several contexts. In certain very limited circumstances they are used to make plural forms of words. They are used to make contractions of two words into one. Most frequently in formal writing, apostrophes are used to show possessiveness.

Plurals

Apostrophes do not make a word plural. Ever. If you mean to indicate more than one of a person, place or thing, just add s or es to the word:

dishes
phones
pens
blogs

Sometimes we see numbers with apostrophes. Some sources approve this style, but the better practice is to avoid it.

The MLA Handbook, which is the Bible of American punctuation, instructs us not to add apostrophes to pluralize even numbers written numerically:

Olga Korbut scored unprecedented 10s from the gymnastics judges.
Music during the 1990s was unremarkable for the most part.

When the number is spelled out as a word, it is made plural just like any other word. Add only the letter s with no apostrophe:

She was dressed to the nines.
Throughout the nineties I listened to classical rock most often.

Even if it is the plural of an acronym or abbreviation, do not use the apostrophe to make a plural:

Both of us have IRAs.
He has PhDs in both English and Philosophy.
Please return the DVDs to Blockbuster.

This rule having been fully explained, I shall now confuse you by telling you that there are some authorities which say that using an apostrophe to make the plural of letters or numbers, as well as words referred to as words in the context of the sentence, is acceptable. Both formats are correct, so long as the writer is consistent.

There are no if's, and's or but's about it.
There are no ifs, ands, or buts about it.

Shakespeare wrote plays during the 1500's and 1600's.
Shakespeare wrote plays during the 1500s and 1600s.

Those size 14's make his feet look like longboats.
Those size 14s make his feet look like longboats.

Jack had three C's on his report card.
Jack had three Cs on his report card.

The bottom line is that no matter which method you use, be consistent. It just looks silly when we read, "Be sure to cross your Ts and dot your I's." The do's and don't's of this alternately acceptable form might be confusing, I know, so a good rule of thumb might be:

When in doubt, leave the apostrophe out.

Contractions

We can get the contraction rule out of the way quickly since, with one tiny exception, most of us don't have a problem with it. The apostrophe takes the place of one or more dropped letters and the spaces between them. Thus, cannot becomes can't and you are becomes you're. Likewise, you all becomes y'all.

One contraction causes mass confusion. It really should not, because it follows the exact same rule as all others: the apostrophe substitutes for dropped letters. It's is the contraction for "it is" or "it has." The possessive of the word it does not have an apostrophe.

Possesives

Personal pronouns are the pronouns that take the place of a person or the name of something. They NEVER get apostrophes. Personal pronouns are the words mine, yours, his, hers, ours, theirs, and its. That's right: its (with no apostrophe) denotes possessiveness.

You don't see mine's, your's, her's, hi's, our's, or their's. Written that way they don't even look right, now do they? Personal pronouns never get apostrophes. They do not want them. They are apostrophe-deprived and they like it that way. Unlike nouns that don't have people associated with them, personal pronouns are apostrophe snobs. Don't ever give a personal pronoun, even an it, an apostrophe. You will be ridiculed and scorned by personal pronouns everywhere if you violate this rule.

Other than the personal pronouns mine, his, hers, yours, ours, its, and theirs, possessiveness is indicated by - you guessed it - an apostrophe followed by the letter s.

To wit:

John's blog (the blog of John)
The mansion's location (the location of the mansion)

If you can rephrase to say the x of y, then y's x will need the apostrophe.

When the noun having possession is singular, meaning that there is only one of that particular thing, the apostrophe followed by the letter s is an absolute, unbreakable, indefatigable rule. Always, always, always add an apostrophe and an s to indicate that the noun has something it otherwise would not.

One week's time (the duration of one week)
One mile's distance (the distance of one mile)
The pencil's lead (the lead of the pencil)
The girl's shoe (the shoe belonging to the girl)

If you can rephrase the phrase as one thing of another, you have a situation on your hands in which you should use an apostrophe.

This is true even when the singular noun ends in the letter s. That's right: add the apostrophe and the s even if the word ends in s, so long as the word is singular and not plural:

The goddess's nectar and ambrosia (the nectar and ambrosia belonging to the goddess)
The princess's jeweled tiara (the costly diadem of the princess)

Another authority says that when the word ends in s the apostrophe goes after even if the word is singular. If you are in doubt, add the s.

If the possessing noun is a plural, and ends in s, just add an apostrophe. The s is already there. The apostrophe does not separate the s that creates the plural from the rest of the word.

The dogs' collars (the collars of the dogs)
The boys' ball (the ball belonging to the boys)
Two weeks' notice (notice of two weeks before leaving one job for another)
Five years' duration (the eternity of some marriages)
The horses' watering trough (the watering trough of the horses)
The twelve dancing princesses' tattered slippers (remember that fairy tale?)

However, if the possessing plural noun does not end in the letter s the apostrophe and - you guessed it - the s is needed:

Children's stories
Men's ties
Women's suffrage

When a proper name ends in an s, and there are more than one of these proper names indicated in the context, the name is pluralized by adding es the same was other nouns ending in s are made plural. It is made possessive by adding just an apostrophe, the same as other plural nouns ending in s.

Here is an example of a proper noun ending in s in its singular form: "Bridget Jones's diary was found on the coffee table." The sentence means that the diary of one Ms. Jones was found in a scandalously public place. Please note that the diary is not of Bridget Jone, so the s remains on Jones and an apostrophe and another s is added to make the possessive.

When the name Jones is made plural, just as with any other noun ending in s, we add es. We then add an apostrophe but no additional extra s to indicate the possessive.

The Joneses live here. (Bridget's mum and dad reside in this house)
The blue cottage is the Joneses' vacation getaway. (That little house belongs to the entire Jones family.)
Welcome to the Joneses' beach house.(All of the members of the Jones family welcome you)