What is Apostrophe S ('s)?
Apostrophe s ('s) is used in English to show that something belongs to someone or something. It shows possession or ownership. We add 's to a noun to show what it owns. This is called the possessive form. For example, if a book belongs to Sarah, we say "Sarah's book."
How to Use Apostrophe S
The basic rule is simple: add apostrophe + s to the owner's name or noun. If the noun is singular (one person or thing), add 's. If the noun is plural and already ends in -s, add only the apostrophe after the s. For example: "the students' classroom" (many students, plural). Remember: apostrophe s comes BEFORE the thing that is owned.
Singular vs Plural Nouns
| Noun Type | Rule | Example |
|---|---|---|
| Singular nouns | Add 's | John's car, the teacher's book, my friend's house |
| Regular plural nouns (ending in -s) | Add apostrophe only | the teachers' books, the students' classroom, the cats' toys |
| Irregular plural nouns (not ending in -s) | Add 's | the children's toys, the women's room, the men's coats |
Irregular plural nouns do not follow the standard -s pattern. Common examples include "children," "women," "men," "feet," and "geese." Because these plurals do not end in -s, you should add 's to show possession, just as you would with singular nouns.
Singular vs Plural Possessives: Side-by-Side Comparison
| Category | Singular Noun | Regular Plural Noun (ends in -s) |
Irregular Plural Noun (does not end in -s) |
|---|---|---|---|
| Rule | Add 's to the end of the noun | Add only an apostrophe (') after the existing -s | Add 's to the end of the noun (same as singular) |
| Base Noun | dog | dogs | children |
| Possessive Form | dog's | dogs' | children's |
| Example Phrase | the dog's collar | the dogs' collars | the children's toys |
| More Base Noun Examples | cat, teacher, James, company | cats, teachers, companies, students | men, women, mice, geese, people |
| More Possessive Examples | cat's, teacher's, James's, company's | cats', teachers', companies', students' | men's, women's, mice's, geese's, people's |
| More Example Phrases | the cat's food; the teacher's desk; James's car; the company's policy | the cats' food; the teachers' lounge; the companies' profits; the students' books | the men's team; the women's room; the mice's nest; the people's choice |
| When to Use | When only one owner is referred to | When more than one owner is referred to and the plural already ends in -s | When more than one owner is referred to but the plural does not end in -s |
| Number of Owners | One (1) | Two or more (2+) | Two or more (2+) |
| Ends in -s Before Apostrophe? | No (apostrophe + s added) | Yes (apostrophe only added) | No (apostrophe + s added) |
| Common Mistake to Avoid | Writing dogs (no apostrophe) instead of dog's — this is just a plural, not possessive | Writing dogs's — never add 's after an existing plural -s | Writing childrens' — do not treat irregular plurals like regular ones; always add 's |
| Special Case: Names Ending in -s | Both James's and James' are widely accepted; follow your style guide consistently | N/A | N/A |
| 🔑 Key Difference: The deciding factor is always the plural form of the noun, not simply whether it ends in -s. If the plural already ends in -s (regular plurals like dogs, teachers, companies), add only an apostrophe after the -s. If the plural does not end in -s (irregular plurals like children, men, women), treat it exactly like a singular noun and add 's. For all singular nouns, always add 's regardless of their ending. | |||
Formula
Formula
singular noun
+
's
+
noun (thing owned)
The teacher's desk is very organized.
Examples
This is Maria's phone.
Singular possession · ownership
The cat's toy is under the bed.
Singular possession · family relationship
My parents' house is very big.
Plural possession · family
The boys' shoes are in the hallway.
Plural possession · object ownership
Sarah's sister works at the hospital.
Singular possession · family relationship
The children's playground is closed today.
Irregular plural possession · location
When to use it
Family relationships
Use 's to show family connections and relationships between people.
"My mother's sister is my aunt."
Personal belongings
Show what things people own or have with them.
"Tom's backpack is blue."
Places and spaces
Show which person or group a place or space belongs to.
"The doctor's office is on the second floor."
Time expressions
Use 's with time words to show duration or timing.
"We have two weeks' holiday in December."
Signal words
belongs to
of
ownership
possession
singular
plural
irregular plural
Common Mistakes
✕
Wrong
The book is of Sarah.
✓
Correct
The book is Sarah's.
In English, we use 's to show possession, not 'of'. We say 'Sarah's book', not 'the book of Sarah'.
✕
Wrong
The teachers books are heavy.
✓
Correct
The teachers' books are heavy.
For plural nouns ending in -s, add only the apostrophe, not 's. Many teachers = teachers' books.
✕
Wrong
Johns car is red.
✓
Correct
John's car is red.
Always use an apostrophe before 's' for singular possessives. Without the apostrophe, it's just a name.
✕
Wrong
The childrens' toys are fun.
✓
Correct
The children's toys are fun.
Children is an irregular plural (doesn't end in -s), so use 's, not just an apostrophe.
KEY TAKEAWAYS
What to Remember
- Add 's to singular nouns to show possession, for example: Sarah's book or the cat's toy.
- For plural nouns ending in -s, add only the apostrophe after the s, for example: the dogs' house.
- The possessive form shows that something belongs to or is owned by a person or thing.
- Use apostrophe s to connect the owner to what they own in a single phrase.
- Don't confuse possessive 's with contractions like it's (it is) or they're (they are).