The Apostrophe - how and when to use it

The Apostrophe - when to use it, and when not to!

What is an apostrophe?

An apostrophe is a small ' mark which frequently indicates where one or more letters have been left out of a written word. (The word "apostrophe" is derived from Ancient Greek words meaning roughly "the stroke of turning-away").

Some examples of its use include:

• I'm (I am)
• don't (do not)
• isn't (is not)
• can't (can not)

In written English, the apostrophe is used most commonly in two situations - missing letters, and possession.

Rules of Thumb

These will cover nearly all cases, and will help if you are unsure where or whether to use an apostrophe.

1. Plurals

If you are using a word in the plural (referring to several objects) then you should not use an apostrophe.
Example: The dogs ate all the biscuits.
Exceptions: Symbols and numerals are often given an apostrophe when used in the plural.
Example: He underlined all the &'s and the 6's and 7's.

2. Possession, singular

If you are writing about a single object which owns or possesses something, you should generally add an apostrophe-s.
Example: The dog's kennel was outside.
Exceptions: The most important and confusing exceptions are the words 'it' and 'who', which do not take an apostrophe to indicate possession. Also, the words 'your' and 'their', which are already possessive words, do not take an apostrophe when an -s is added.
Examples: The dog ate its biscuits. The man whose dog ran away. That dog is bigger than yours. Your cat is bigger than theirs

3. Possession, plural

When a plural object owns or possesses something, it is generally given a final apostrophe if the plural is formed by adding an -s. If the plural is formed some other way, then an apostrophe-s is added to indicate possession,
Examples: The dogs' owners formed a society. The houses' chimneys were damaged. The children's toys were stolen. Everyone's signature is different.

4. Shortening 'is' or 'has'

Particularly when speaking, and sometimes when writing, the words 'is' and 'has' can be shortened to an apostrophe-s after the previous word.
Examples: The dog's eating some biscuits. The rain's filled up that bucket. It's half past two. Who's next?

5. Shortening 'are'

In a similar way, when a word is followed by 'are' it can be shortened to apostrophe-re. The shortened word is easily confused with others which have the same sound but are spelled differently - it will help to remember the rule that if you can replace the 'r' sound with the word 'are' then you should use an apostrophe.
Examples: We're going out tonight. They're coming with us. You're going to have fun.
Examples of words that sound the same but are spelled differently: We were out last night. Where did we go? Look over there. Is that their house? Is it your house?

6. Other missing letters

An apostrophe is written in many cases where a word or words are shortened in common speech. 
Examples: I'm ready. I can't see it. We'll meet tomorrow. He'd never go there again. The cat'll catch the mouse.

It is occasionally possible for more than one apostrophe to be in the same word - "shall not" can be abbreviated to "sha'n't" (although it is usually written "shan't" nowadays), and "forecastle" to "fo'c's'le".

In general the rule is to replace any group of one or more missing letters with a single apostrophe.

Sometimes the abbreviation indicates an old way of spelling or pronouncing a word which is no longer in use - "will not" is contracted to "won't" because it used to be "woll not" in Old English. As a matter of interest, the possessive apostrophe-s ending is often attributed to the fact that in Old English the possessive (genitive) form of a noun ended in -es, and the 'e' is now omitted.