In English, it has two jobs:
- To show where one or more letters have been left out (as in the abbreviation (contraction) of do not to don't).
- To show the possessive case (as in the cat’s whiskers).
Its versus it's
The most common grammatical mistake in written English is to put it's where its is correct.
- The cat chased its tail. (correct)
- The tyre lost it's grip. (wrong)
It's: a contraction of the verbal phrase it is or it has.
- It's mine. (correct; check: It is mine)
- It's been here. (correct; check: It has been here)
- The cat chased it's tail. (wrong; cannot be expanded to it is)
The same applies to yours, theirs and ours because these are also possessive adjectives of personal pronouns.
- The colour is ours.
- That book is hers (or his).
- Theirs was the responsibility.
Apostrophes are also used to show something belongs to someone (or something). Again, correct uses can be expanded:
- Mike's car. (correct: the car that belongs to Mike)
- The dog's ball. (correct: the ball that belongs to the dog)
- Those dog's are large. (wrong: cannot be expanded. Here "dogs" is a plural word)
The intrusive apostrophe
- Mrs. Jones' hat or Mrs. Jones's hat. (both correct)
- Both of my parents' birthdays. (correct)
- CD's and DVD's (wrong because not necessary: see "Plural" section below)
- Apple's and pear's (wrong)
Writing dialogue or titles
Apostrophes are also used when other words are shortened, as in slang:
- Go get 'em tiger! or Li'l Bow Bow.
This is just a version of the abbreviation function.
To make a word that doesn't (does not) usually exist as a plural into a plural, an apostrophe is occasionally used. See these examples:
- How many A's did you get this year? Here it is wrong because it is not needed.
- The poll received many yes's and very few no's. Here it is sensible because without it the words 'yess' and 'nos' look quite peculiar. General rule: if an apostrophe is not needed, do not use it.
- Quirk, Geenbaum, Leech & Svartvik, A comprehensive grammar of the English language. Longman, London & New York. p985 Template:Catalog lookup linkScript error: No such module "check isxn".