by Charlotte Beckham, proofreading and editing professional at Cambridge Proofreading Ltd.

The apostrophe is quite possibly the most commonly misunderstood punctuation mark in the English language. You can lose a lot of credibility in your writing by failing to grasp the correct usage of apostrophes. Don’t worry though; the basic concepts of the apostrophe are relatively straightforward. The primary functions are the following:

  • To make nouns and pronouns possessive
  • To show the omission of letters in words

Possessive singular nouns

The most fundamental usage of an apostrophe is for possessive nouns. Let’s begin by breaking down what is meant by this term. A noun refers to a person, place or object. Therefore, a possessive noun must describe ownership to someone or something.

The easiest example to consider is that of the singular (i.e. only one) noun. In the following, “David” is described as the owner by placing “’s” at the end of the noun.

“David’s car was blue.”

Possessive plural nouns

Many writers make mistakes with regards to the possessive plural noun. Usually, a plural noun has an “s” at the end of the word (referred to as a regular plural noun). To mark a regular plural noun as possessive, you only need to add an apostrophe to the end. You do not add another “s”.

“The puppies’ paw prints were all over the house.” – Correct

“The puppies’s paw prints were all over the house.” - Incorrect and really difficult to say, unless you are Gollum.

You should also be aware of plural nouns that don’t end with an “s”. For example, you may think that “people” is a plural as it means more than one person, but it can also be treated as a single entity.

“The Volkswagen Beetle was the people’s car.”

A final word of caution is to remember that English is a mongrel language, with influences from Latin, Greek and French, and many other languages. Many Latin words used in science and maths are pluralised with an “i” rather than an “s” (e.g. “nucleus” becomes “nuclei”). Here is a great observation from Steve Coogan’s, Alan Partridge:

Alan: “It’s interesting that since owning a Lexus it’s amazing the number of Lexi that you notice…because that’s the plural, Lexi...”


To make communication more efficient, we often drop letters from words, particularly with contracted and conjunctive words. This is where you combine two words in to one (e.g. “do” and “not” can be contracted to “don’t”). The apostrophe simply marks where the letter has been removed.

While contractions are sometimes frowned upon in academic writing, they can be useful to show slang or colloquial language in literature:

“You talkin’ to me?”

This short guide should have given you the information that you need to tackle using the apostrophe correctly. I dream of a utopia in which markets sell “apples” rather than “apple’s”, and where internet bloggers and Facebook updaters will be confident in differentiating between “your” and “you’re”.  

If we work together, we can protect the apostrophe as an important tool in inferring more meaning from our written language.

More on punctuation