A misconception about the apostrophe is that it is used only in contractions (e.g. cannot -> can’t). Thus, many times, it is not used or used incorrectly in other situations. Besides the comma (,) and period (.), the apostrophe is also a very important and commonly-used punctuation mark. Therefore, we need to have a good grasp of it. Here are some of its usages:
1) Contractions should not be used in formal academic writing as many teachers still frown upon them. Instead, they should be reserved for speech and informal settings. In fact, native speakers use contractions all the time in speech.
I am = I’m
you are = you’re
let us = let’s
do not = don’t
it is = it’s
2) It is used in possessives. With singular nouns, the apostrophe goes after the noun, followed by a “s”. With plural nouns, the apostrophe goes after the “s”.
The boy’s hats are in his room. (one boy)
The boys’ hats are in their rooms. (more than one boy)
What do we do with plural nouns which do not end with “s” but are irregular in spelling (e.g. children, women, men, teeth)? Here, the apostrophe comes before the “s”.
The children’s hats are in their rooms. (more than one child)
The woman’s hats are in her closet. (one female)
The women’s hats are in their closets. (more than one female)
There is an apostrophe in the contraction “it’s”, which stands for “it is” or “it has”, but it is not in the possessive form “its” (e.g. The dog lost its collar.)
3) It is used to indicate the omission of figures in dates or letters in words. The omission of figures in dates is still quite commonly seen (e.g. 2009 -> ’09). On the other hand, omission of letters in words is less prevalent now than in old English, such as Shakespearean English, but still seen in modern poems or to imitate non-standard English forms.
The prologue of Shakespeare’s Romeo and Juliet portrays old English and also contains examples of the apostrophes used in possessive forms:
A pair of star-cross’d lovers take their life;
Whole misadventured piteous overthrows
Do with their death bury their parents’ strife.
The fearful passage of their death-mark’d love,
And the continuance of their parents’ rage,
Which, but their children’s end, nought could remove,
Is now the two hours’ traffic of our stage;
The which if you with patient ears attend,
What here shall miss, our toil shall strive to mend.
4) It may be used to indicate the plurals of letters or words. This is especially important to clearly differentiate the plural from, perhaps, another word (e.g. A’s versus As). Nowadays, we do not add an apostrophe to make plural a year or an abbreviation, where there are no periods.
I got all A’s on my report card.
What are the do’s and don’t’s in the American home?
BUT: The Civil Rights Movement in the United States started in the 1950s.
One of my colleagues has multiple PhDs.