The apostrophe (’) is one of the most misused punctuation marks in English, yet, as Cambridge Grammar explains, its rules are quite straightforward once you understand the two core functions it serves. First, the apostrophe marks possession — showing that something belongs to someone or something. Second, it marks contraction — showing that one or more letters have been left out when two words are combined. Apostrophes are never used simply to form a plural, a mistake so common it has its own nickname: the greengrocer’s apostrophe. Whether you are writing an essay, a professional email, or preparing for an English exam, understanding apostrophe rules is essential for accurate, polished writing.
Formation / Rules
| Use | Rule | Example |
|---|---|---|
| Singular possessive | Noun + ’s | the cat’s tail, James’s book |
| Plural possessive (ends in s) | Noun + ’ | the dogs’ leads, the teachers’ room |
| Plural possessive (irregular) | Noun + ’s | children’s toys, men’s shoes |
| Contractions | Replace omitted letter(s) | don’t, it’s, they’re, I’ve |
| Omitted digits | Apostrophe before number | the ’90s, class of ’08 |
| Plural — no apostrophe | Never use ’ for plurals | CDs, MPs, potatoes (not CD’s) |
Examples
- The teacher’s desk is near the window. (singular possessive)
- The students’ essays were excellent. (plural possessive — ends in s)
- The children’s playground is closed today. (irregular plural possessive)
- It’s raining outside. (contraction: it is)
- The cat licked its paw. (possessive pronoun — no apostrophe)
- Don’t forget your homework. (contraction: do not)
- She grew up in the ’80s. (omitted digits)
- Is that your bag or hers? (possessive pronouns — no apostrophe)
- The boss’s office is on the top floor. (singular noun ending in s)
- They’re coming to the party tonight. (contraction: they are)
Common Mistakes
| Wrong | Correct | Explanation |
|---|---|---|
| The dog ate it’s food. | The dog ate its food. | ‘Its’ is a possessive pronoun; no apostrophe needed. |
| DVD’s on sale today. | DVDs on sale today. | Apostrophe never forms a plain plural. |
| The womens’ team won. | The women’s team won. | Irregular plural needs apostrophe + s. |
| Your late for class. | You’re late for class. | ‘You’re’ = you are (contraction). |
| The childrens room. | The children’s room. | Possessive requires apostrophe + s after irregular plural. |
Practise
Grammar Quiz
Choose the correct apostrophe form for each sentence.
Cloze Dropdown
Select its/it’s, your/you’re and other tricky pairs.
Complete the Sentence
Rewrite phrases using the correct possessive apostrophe.
Practice What You’ve Learned
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Frequently Asked Questions
What is the apostrophe used for in English?
The apostrophe has two main uses: forming possessives (the dog’s lead) and marking contractions where letters are omitted (it’s = it is, don’t = do not). It is never used to form a plain plural.
How do I form the possessive of a singular noun?
Add apostrophe + s to any singular noun: the cat’s tail, James’s book, the company’s policy. This applies even when the noun already ends in s.
How do I form the possessive of a plural noun?
If the plural ends in s, add only an apostrophe: the dogs’ leads, the teachers’ lounge. If the plural does not end in s (irregular plurals), add apostrophe + s: children’s books, men’s shoes.
What is the difference between its and it’s?
‘Its’ (no apostrophe) is the possessive pronoun: the cat licked its paw. ‘It’s’ (with apostrophe) is the contraction of ‘it is’ or ‘it has’: it’s raining, it’s been a long day.
Should I write James’ or James’s?
Both are acceptable. Most modern style guides (Chicago, APA) prefer James’s. The Times and some British publishers use James’. Consistency within a document matters most.
Do possessive pronouns need an apostrophe?
No. Possessive pronouns (its, his, hers, ours, yours, theirs, whose) never use an apostrophe. Apostrophes with pronouns always mark contractions: it’s, who’s, you’re, they’re.
When do we use apostrophes with dates and acronyms?
For decades and years, write the 1990s or the ’90s (apostrophe replaces omitted digits). For acronyms, write MPs, DVDs (no apostrophe for plurals). Use an apostrophe only for the possessive: the MP’s vote.
What is the greengrocer’s apostrophe?
The greengrocer’s apostrophe is incorrect use of an apostrophe to form a plural: apple’s for sale, DVD’s available. Plurals do not need apostrophes; this is one of the most common punctuation errors in English.
How do I write joint possession with apostrophes?
For joint possession (one thing shared), add apostrophe + s only to the last name: Jack and Jill’s house. For separate possession (different items), add apostrophe + s to each: Jack’s and Jill’s cars.
Are apostrophe errors penalised in English exams?
Yes. In IELTS, Cambridge, and Duolingo English Test writing tasks, apostrophe errors affect your Grammatical Range and Accuracy score. Confusing its/it’s or your/you’re is particularly noticeable to examiners.