The apostrophe has to be the most misused punctuation mark in the English language. World-wide web and internet users are some of the worst culprits, but there are increasing numbers of wrongly placed apostrophes appearing in professional publications. Occasionally, the apostrophe can change the meaning of a sentence, so misusing it can confuse the reader. However, the problem is usually that it is annoying and distracting for people who understand apostrophes, and can look very bad - it hardly fills potential customers with confidence to see poor punctuation in an advertisement, especially if you are advertising a CV or web-page writing service (I have actually seen examples of this in national newspapers in the past).
On this page, I have provided a brief guide to the apostrophe, and I also plan to provide links to similar pages if I find them. Please note that this is not an American-sourced explanation, so the rules stated are not American English (which can often be a problem with information on the world-wide web). That's not to say that American punctuation rules are any different!
Using the apostrophe to show the possessive case
The apostrophe is used to show when something belongs to someone, i.e. it is used in the possessive case:
- For nouns ending in any letter other than s, simply add 's (the apostrophe preceding the s). This applies to both singular and plural nouns. Examples: car's bumper, men's hats, box's lid
- Singular nouns ending in s are treated no differently, 's should still be added. Examples: class's teacher, atlas's index
- The final s is usually omitted when it is silent in speech. Example: for goodness' sake
- For plural nouns ending in s, an apostrophe is added after the final s. Examples: classes' teachers, boys' clothing
- In proper names and surnames ending in s, add 's just as for all other nouns. Examples: James's house, Gauss's law
- The are three occasions where the final s is omitted from proper nouns:
- When the s does not sound correct in speech. Example: Bridges' poems
- In ancient and biblical names. Example: Moses' law
- When the name has three or more syllables. Example: Archimedes' principle
Pronouns in the possessive case
When using pronouns such as his, hers, its, ours, theirs or yours, an apostrophe should not be used. No-one would write hi's, and few would write her's, but a very common mistake is to use it's instead of its. It's is an abbreviation for it is, and is NOT a pronoun! Example: The book was in its place on the shelf
Most words are pluralised by adding an s. It is wrong to add an apostrophe in this case. Example: the plural of apple is apples (not apple's). One exception to this is abbreviations, where it is now acceptable to add an apostrophe. Example: the plural of MP is MP's It is, however, always correct to write MPs without an apostrophe, and this is probably the preferred convention.
Using the apostrophe to show the omission of letters
The apostrophe is used to show where a letter or letters are omitted from an expression, usually in speech. Examples: he's (he is), don't (do not), I'll (I will). Important notes: Do not confuse it's (short for it is) with its (a possessive pronoun). Also, do not confuse who's (short for who is) with whose (another pronoun, possessive case of who).
Archaic words such as canst and shouldst do not need apostrophes, as they are not formed by omitting letters from another word.
Some shortened forms of words are more common than their full-length counterparts, and the apostrophe is often left out. Example: cello (or 'cello, short for violoncello).