Apostrophes have two main functions. They are used to show a relationship where one thing belongs to another. They are also used in contractions when two words are pushed together and a letter or two are left out.
Apostrophes and Possessives
Do you ever wonder why some non-native speakers have such a colorful way of expressing themselves? English speakers are a lazy lot. If there is a way to shorten something, we’ll do it. Instead of saying, The book that belongs to Mary is on the table, English speakers say, Mary’s book is on the table. The apostrophe s is shorthand for belongs to. Let’s try another one. After school I’m going to Cathy’s. While you probably wouldn’t write a sentence this way, its meaning is clear. After school I will go to the house of Cathy. But that sounds just wrong. Too stuffy.
We use the word possessive to show a relationship when one thing belongs to another. So in the phrase Mary’s book, the book belongs to Mary, she possesses the book. In The phrase Cathy’s house, it is the house that belongs to Cathy. We use apostrophe s to show possession between things too. Jack toots the car’s horn. The horn belongs to the car. Last night’s dinner was a disaster. The dinner of last night was a disaster.
Plural possessives can get complicated. There are two major styles for writing: AP style and Chicago style. They each treat plural possessives differently. If you are a student, follow your teacher’s instructions. If you are just trying to understand apostrophes, check out this link https://apvschicago.com/2011/06/apostrophe-s-vs-apostrophe-forming.html, then choose a style and stick to it.
Possessive Pronouns
Now that I’ve filled your head with the use of apostrophes to show possession, I want to introduce you to possessive pronouns. Remember, a pronoun is a word that takes the place of a noun: I, you, he, she, it, we, they. Possessive pronouns refer to things or people that belong to someone. These include: mine, yours, hers, his, ours, theirs, and its. Notice there are no apostrophes in any of these words! Since they already indicate possession they don’t need an apostrophe.
Contractions
Another shortcut English speakers take is the contraction. Some common contractions that you will recognize are: don’t, can’t, shouldn’t. Each of these combines a verb with the word not: do not, can not, should not. The apostrophe replaces the o in not.
Other words commonly used in contractions are have (we’ve, should’ve), is (here’s, it’s), will (I’ll, she’ll), are (you’re), and had or would (he’d, there’d).
Common Apostrophe Errors
Never use an apostrophe s to make a plural. More than one apple is apples, not apple’s. This applies to days of the week, too. Open Saturday’s is not correct. It should be Open Saturdays.
You don’t need an apostrophe with dates and numbers. Music in the 70s was groovy. The sky was filled with 100s of balloons.
But my personal pet peeve is confusing possessive pronouns for contractions. Words like you’re and your, it’s and its may sound the same, but they have completely different meanings. You’re is a contraction that means you are. Your is something that belongs to you. It’s is a contraction of it is. Without the apostrophe s, its is a possessive pronoun: the milk is past its expiration date.
Apostrophes are a convenient shortcut once you learn how to use them.
