One use of the apostrophe is in contracted words. The apostrophe is used to indicate that a letter or letters has/have been removed. If you follow this rule then it will avoid confusion about where the apostrophe should be.
He is = he's
I am = I'm
Do not = Don't
They have = They've
It is = It's
I would = I'd
Let us = Let's
She has = She's
Who is = who's
This is not an exhaustive list of contractions. There are many more but all follow the same rule. In examples such as "she'd" (the contracted form of she would) the apostrophe replaces several letters. Obviously, only one apostrophe is needed to indicate that several letters have been omitted.
You need to be a bit careful with apostrophes; many people make the mistake of putting them in all over the place. Contracted forms are very common in spoken language but should not be used in a formal academic essay. In formal/academic writing you must use the full, unabbreviated form.
Clayton does not find any evidence that densely amnesiac patients show reduced performance on other measures of working memory.
There is no doubt that successive presidents of the United States have found difficulty in balancing pressures from home and abroad.
The only place they could legitimately appear is in quotations.
"I'm drowning!!" he shouted.
Test your understanding of contracted words with this exercise.
The apostrophe showing possession.
Before reading on, you can have a go at this question if you would like. If not, read on and have a go at the exercise at the end.
Tick the sentences, which use the apostrophe correctly to indicate possession.
A second and trickier use of the apostrophe is to show possession. If the possessor is a singular noun, an -'s is added to the end of the noun. This is true for both proper nouns (people and places beginning with a capital letter) and common nouns (other nouns). Here are some examples of the apostrophe at work showing possession:
He found himself lost in Madrid's winding streets.
I cannot understand Tim's point of view.
The building's foundations were very unstable.
The poet's work was highly regarded around the world.
A very common mistake is to put apostrophes where they should not be. Many people, unsure about using the apostrophe, put it in every time they see a word ending in s. Grammar checkers do not always highlight this mistake, as they do not know the meaning of the sentence.
Bristol contain's a lot of lovely old building's and street's.
If the possessor is a plural noun ending in s, simply adding an apostrophe after the final s indicates possession.
The teacher was always losing her pupils' books.
The monks' meals were served in a cold and damp dining room.
I can never understand the politicians' obsession with spin.
As you can see, the positioning of the apostrophe makes a big difference to the meaning of the sentence. Make sure when adding the apostrophe that it indicates your intended meaning very precisely.
The monk's meals were served in a cold, damp room. (one monk)
The monks' meals were served in a cold, damp room. (lots of monks)
If the plural noun does not end in an s, the addition of -'s shows possession.
The children's books lay on the table.
The men's boots were lined up outside the door.
The women's race will take place before the children's race.
If the possessor is a singular noun that happens to end in an -s, there is some debate about whether the apostrophe is simply added after the -s or whether an -'s is needed.
It appears that both are acceptable. Whichever you decide to use, make sure you are consistent. The university English department's style guide recommends that proper nouns that end in -s form their possessive form by adding -'s.
Have you seen James' book?
Have you seen James's book?
The exceptions to this rule are proper nouns that are Latin or Greek in origin.
Odysseus' adventures spanned many miles and many many years.
Pythagoras' theorem has baffled generations of school children.
Test your understanding of the apostrophe with this exercise.