Apostrophe

The apostrophe ( ' or ' ) is a punctuation mark, and sometimes a diacritical mark, in languages that use the Latin alphabet or certain other alphabets. In English, it serves a few purposes, but mainly to indicate the marking of the omission of one or more letters (as in the contraction of do not to don't).

Rules to follow when using an apostrophe

The apostrophe (') is a punctuation mark that is sometimes used diacritically in Latin languages. In English, it serves the following three purposes:

• To denote the absence of certain characters in contractions (aren't, won't, didn't)

• To mark possessive case (the elephant's tusk, a day's work)

• To indicate more than one item of something that isn't actually a word (the three R's) 

The apostrophe was adopted to the English language during the 1500s in emulation of French usage. Apostrophes mark the missing letters in contraction words, in which two words become one for the sake of brevity. The following example shows how the use of contractions can  make a sentence sound more succinct:

• succinct: Nigel and Vivienne won't be able to greet us at Heathrow because they're not due back in London for three weeks.

• cumbersome: Nigel and Vivienne will not be able to greet us at Heathrow because they are not due back in London for three weeks.

Notice how the first sentence roles off the tongue much easier; also consider that in the cumbersome version, the words "will" and "are" raise the possibility that others might misread or mishear the sentence. 

Other rules to follow

When an apostrophe is used to indicate ownership, the mark is placed between the name of the person or thing and the added "s," such as in the following examples:

• Leo's Porsche is bright red.

• It was the most that I could do in a day's work.

When possession is being attributed to a person or thing that has a name that ends in the letter "s," the apostrophe is placed after that final character:

• James' taste in music is too gloomy for me.

• Those mints contain an ingredient derived from horses' hooves.

In sentences where ownership is being collectively attributed to two or more people, the apostrophe is only placed at the end of the last name mentioned before the object in possession:

• In Helsinki, my favorite place to party was at Pekka and Jukka's apartment.

• Terry and Gabe's Goth/New Wave night on Thursdays draws a much more interesting, well-dressed, and music-savvy crowd than Wayne and Sitoki's EBM/Industrial night on Fridays.

When two subjects within a sentence are both attributed individual ownership, both names end with apostrophes:

• Carrie's step-mom and Phillip's dad seem to be carrying on an affair with one another, despite the fact that both are engaged.

• A lion's mane and a tiger's stripes are much more attractive than a platypus' beak.

One notable example of contractive and possessive apostrophe rules coming into conflict is with the word "it's." As a contraction, the mark is used to signify the joining of the words "it" and "is." Since the word functions as a possessive pronoun in its other form (ex. the cat lost its yarn), it doesn't need an apostrophe to indicate ownership.

There is some controversy over the placement of apostrophes in abbreviated decades. While there's no absolute right or wrong on this issue, decade spellings could be ranked as follows:

• Preferable: The '80s were the best decade for hairstyles and fashion.
• Acceptable: The 70's was the best decade for musical innovation.
• Awkward: The '00's were one lengthy bore, and the '10's aren't shaping up to be much better.