Apostrophes have two essential uses in the English language. They are used to form contractions, a combination of two words. Common examples of apostrophes in contractions include: do not turns into don’t, can not into can’t, will not into won’t, they have into they’ve, and we are into we’re. In contractions, apostrophes generally stand for the missing letters of the second word, although won’t is an exception.
The second use of apostrophes is to indicate possession. In this case, the apostrophe suggests possessive connection between a subject and noun. Examples include: Nancy’s car, Bill’s idea, Harold’s use, and the boy's stuffed animals. There are a few words in the English language that indicate possession without requiring an apostrophe. These are possessive pronouns like my, his, hers, its, theirs, yours, or ours. There is no need to include an apostrophe with these words because the pronoun already indicates possession. In fact, a common mistake is to use the word it’s to indicate possession. It’s is actually a contraction of the words it is, and incorrect use can obscure meaning.
A common mistake in using apostrophes is to use one whenever you add an s to a word to make it plural. Unless you are indicating possession of something, a plural word never needs an apostrophe. Here is an example of incorrect apostrophic use:
- The parent’s were happy the school year had begun.
By using an apostrophe in this way, this sentence would read:
- The parent is were happy the school year had begun.
Instead of expressing a plural, the apostrophe use here makes the word a contraction of the words parent and is. Correct usage would not include an apostrophe. The sentence should be written:
- The parents were happy the school year had begun.
The rules about what to do with apostrophes and words that end in an s can be a bit complicated. Some generalize the rule to be that you can add an apostrophe s or just the apostrophe. That is, whether you write Dickens' or Dickens's is a matter of personal preference.
Many sources, including Strunk and White's Elements of Style and Purdue's Online Writing Lab (OWL), provide different, and a bit more complicated, rules. Both of these sources note that the apostrophe and the additional s should generally be added regardless of the word's last letter. So, it would be Dickens's or Charles's, and not Dickens' or Charles'. The last s however, should be omitted in the following circumstances:
- possessives of ancient proper names that end in "es" or "is" (e.g., Socrates'),
- the possessive of Jesus (i.e., Jesus'), and
- plural nouns that end with an s (e.g., houses' or friends')
It's also important to note that an apostrophe and an s should be added to the end of a word that changes forms, rather than ends in an s, when it is pluralized. For example the plural form of child is children, and the plural of mouse is mice. To indicate possession with these types of words, you add an apostrophe and an s following it. For example: The children’s rooms were very messy or The mice’s main worries were surviving the winter. These should not be written as childrens’ and mices’.
When a plural word is the same as a singular word, such as the word fish, apostrophes can get a bit more confusing. If you are discussing a single fish, the correct form is fish’s to indicate possession. Words that are pluralized with es, generally indicate possession by placing the apostrophe at the end of the word. Some scientists use the term fishes to talk about more than one species of fish at the same time. For example: The difference in these fishes’ habitats is amazing.
When thinking about when to use apostrophes, it’s important to remember their two uses, possession and contraction. Apostrophes don’t belong when you are not attempting to bring two words together or to indicate possession. Remembering this, and keeping a good style manual handy can help you decide how to use them correctly, and determine exceptions that may exist with individual words.