The apostrophe is one of the most frequently misused punctuation marks. Being uncertain about the rules, some writers avoid it, while others use it inconsistently and often incorrectly. Although the misuse of the apostrophe is unlikely to cause the reader much difficulty, it is worth learning how to use it correctly, not least because some readers may view this type of error as a sign of carelessness or lack of attention to detail.

Here we give some simple guidelines on the use of the apostrophe:

With a noun, to indicate possession

If the noun is singular, use the apostrophe followed by the letter “s”. There is no space between the noun and the apostrophe. Examples:

  • the Prime Minister’s speech
  • Beethoven’s symphonies
  • my brother’s children
  • Charles’s job

With older, classical or foreign names ending in “s”, use the apostrophe only:

  • Ulysses’ voyage
  • Socrates’ work
  • Cervantes’ Don Quixote
  • Guy Fawkes’ night

If the noun is plural, use the apostrophe immediately after the noun:

  • the Students’ Union
  • workers’ rights
  • my brothers’ children

However, if the noun has an irregular plural form, add an “s” after the apostrophe:

  • children’s books       
  • women’s rights
  • sheep’s clothing

In contracted forms

Remember, though, that contracted forms are rarely used in academic writing.       

  • you’re = you are        
  • isn’t = is not
  • can’t = can not
  • it’s = it is 
  • wasn’t = was not 
  • couldn’t = could not
  • he’s = he is
  • don’t = do not
  • shouldn’t = should not
  • they’re = they are      
  • didn’t = did not          
  • mustn’t = must not

And don’t forget that there is a difference between:

  • you’re (you are) and your (belonging to you)
  • it’s (it is) and its (belonging to it)
  • they’re (they are), their (belonging to them) and there (not here)