Apostrophes

• When to use apostrophes
• When not to use apostrophes
• Further reading
• References

When to use apostrophes

The correct use of apostrophes can be difficult. Many people are unsure of when to use them, sometimes adding apostrophes when they're not needed and at other times leaving them out when they should be used!

Apostrophes are used for only two purposes. These are to indicate:

• contraction
• ownership

Contraction

The term 'contraction' refers to the shortening of a single word or two words that are adjacent (next to each other). When two adjacent words are joined together and contracted an apostrophe is used to indicate the omission of one or more letters.

For example:

She's studying for the exam.  She is studying for the exam.
I'd like to finish my assignment. I would like to finish my assignment.
He'll be at the lecture. He will be at the lecture.

Note:
Contractions are NOT generally used in formal academic writing. Contractions are informal and conversational and they do not convey the appropriate formal academic tone generally required for university assignments.

Ownership

The other use of apostrophes is to show ownership (possession) or association.

a. Ownership - singular nouns

To show ownership or association for singular nouns

• write the singular and 
• add an apostrophe followed by s ('s)

For example:

The lecturer's explanation was clear. (That is, the explanation given by the lecturer was clear.)

• write the singular (lecturer)
• add an apostrophe followed by s (lecturer's)

Other examples:

The student's books were expensive. (That is, the books belonging to the student were expensive.)

I took note of the tutor's comments regarding the exam. (That is, the comments were made by the tutor.)

Other uses of the apostrophe followed by s ('s):

Personal names ending in s

There are various and complex rules that are sometimes applied for personal names ending in s. The Style manual for authors, editors and printers (2002) recommends for simplicity that an apostrophe followed by ('s) should be added to any personal name ending in s to show ownership or association:

Professor Collins's book (the book belonging to or written by Prof. Collins)
Dr Saunders's lecture (the lecture presented by Dr Saunders)

Joint ownership

An apostrophe followed by s ('s) is used on only the second of the two 'owners'.
For example, Ben and Nam's assignment, i.e. the assignment jointly done by Ben and Nam

In contrast, where ownership is not joint, each owner takes an apostrophe.
For example, the lecturer's and the tutor's comments, i.e. the comments of the lecturer and the comments of the tutor

b. Ownership - plural nouns ending in s

Most nouns form their plural by adding s.
To show ownership or association of plural nouns ending in s:

• write the plural and
• add an apostrophe after the s (s')

For example:

Students' results will be released on Friday. (That is, the results of more than one student will be released.   

• write the plural (students)
• add an apostrophe after the s (students')

c. Ownership - plural nouns not ending in s

To show ownership or association for plural nouns that do not end in s:

• write the plural and
• add an apostrophe followed by s ('s)

For example:

singular                 plural  NOT ending in s   
man               men
woman           women

The assignment required us to discuss men's attitudes to women's changing roles.
                                                                                         
                                                   attitudes of men          roles of women

• write the plural (men) (women)
• add an apostrophe followed by s (men's) (women's)

In summary:

singular
tutor's comments = comments of one tutor
lecturer's expectations = expectations of one lecturer

plurals ending in s
tutors' comments = comments of more than one tutor
lecturers' expectations = expectations of more than one lecturer

plurals not ending in s
men's attitudes = attitudes of more than one man
women's roles = roles of more than one woman

When not to use apostrophes

1. Apostrophes are often mistakenly used for plurals.

Apostrophes are never used to indicate simple plural, i.e. more than one of any item.

She returned the books to the library. (books NOT book's or books')
Good students usually arrive early for lectures. (students NOT student's or students';
lectures NOT lecture's or lectures')
It is important to contribute at tutes. (tutes NOT tute's or tutes')

Hint

If you're not sure whether a word ending in s needs an apostrophe, try substituting her, his, its or their for the word (Chanock 1997). If it makes sense, it needs an apostrophe; if it does not make sense, no apostrophe should be used.

For example:

the lecturer's explanation - her explanation = the explanation given by the lecturer
                   

This makes sense and therefore the word lecturer needs an apostrophe.

However:

Students conducted a survey - Their conducted...
              
This does not make sense and therefore no apostrophe is used with the word students. (It is a simple plural and does not indicate ownership or association.)

2. Many people confuse it's and its.

• It's is only ever used as a contraction for it is and for it has in examples such as: It's (it has) been decided to postpone the tutorial.

• Its stands for belonging to or associated with it.

At university it's important to submit each assignment by its due date.

A good way to avoid confusing these two is to remember that the word its indicates possession in the same way as, for example, the words my, your, his, her, our and their do. These words do not have apostrophes and, in the same way, neither does its - belonging to it.      

my: belonging to me
your: belonging to you
his: belonging to him
her: belonging to her
our: belonging to us
their: belonging to them
its: belonging to it

3. Your and you're are also frequently confused.

They sound alike but their meanings are entirely different:

• your means belonging to or associated with you.
• you're is a contraction of you are.

You're expected to keep up-to-date with your reading at university.
                                                                 
contraction of 'you are'                 the reading you are required to do

4. Apostrophes are often incorrectly used with shortened forms.

Do not use an apostrophe for plurals of shortened forms. For example: FAQs not FAQ 's; CDs not CD 's.

5. Do not use an apostrophe when referring to decades.

For example write the 1970s, not the 1970's as in 'The 1960s was a time of idealism among university students.'

Further reading

Style manual for authors, editors and printers, 6th edn, 2002, rev. Snooks & Co., John Wiley & Sons, Milton, Qld.

(Chapter 6 - Spelling and word punctuation; Chapter 7 - Sentence punctuation.

References

back to top