Apostrophes and Possession Rules: English Grammar Guide

Apostrophes are small punctuation marks (‘) that play a big role in English grammar. They are mainly used for two purposes: showing possession and indicating contractions. However, they are often misused, especially in plural forms and names. Understanding apostrophe rules is essential for writing clearly and correctly.

This guide explains how to use apostrophes in possessive nouns, contractions, and other special cases with examples and common mistakes to avoid.

What Is an Apostrophe?

An apostrophe (’) is a punctuation mark used to:

1. Show possession – to indicate that something belongs to someone or something.
   Example: Maria’s book means the book belongs to Maria.

2. Form contractions – to show that letters have been omitted.
   Example: Don’t is short for do not.

It’s important to note that apostrophes are not used to form plurals of regular nouns (for example, apples, cars, or dogs do not need apostrophes).

Apostrophes to Show Possession

Possession means ownership or association. To show that something belongs to a noun, we usually add an apostrophe followed by an s (’s).

1. Singular Nouns

Add ’s to show ownership, even if the word already ends in s.

• Example:

  • The cat’s tail (the tail of the cat)

  • James’s car (the car belonging to James)

  • The boss’s office (the office of the boss)

Some style guides allow only an apostrophe (James’ car), but both are correct. Choose one style and stay consistent.

2. Plural Nouns Ending in “s”

If the noun is plural and already ends in s, simply add ’ after the s.

• Example:

  • The teachers’ lounge (the lounge for multiple teachers)

  • The dogs’ park (a park for several dogs)

  • The students’ projects (projects belonging to many students)

3. Plural Nouns Not Ending in “s”

For irregular plural nouns that don’t end in “s,” add ’s to show possession.

• Example:

  • The children’s toys

  • The men’s room

  • The women’s team

These are special plural forms that do not use a final “s” in their base plural form, so the apostrophe + s rule applies.

4. Compound Nouns

When dealing with compound nouns, add the apostrophe + s to the end of the entire compound.

• Example:

  • My brother-in-law’s car

  • The editor-in-chief’s article

If you have plural compound nouns, the apostrophe comes after the plural form:

• Example: The brothers-in-law’s business

5. Joint Possession

If two people share ownership of something, use ’s only after the second name.

• Example:

  • Jack and Emma’s house (they share one house)

If they own separate things, add ’s to both names:

• Example:

  • Jack’s and Emma’s houses (each has a different house)

6. Possession with Names Ending in “s”

This is where writers often hesitate. Should you write Charles’ or Charles’s?

Both are grammatically acceptable, depending on the style you follow:

• Traditional style: Charles’s book

• Modern or journalistic style: Charles’ book

In spoken English, both sound like “Charles’s,” so clarity and consistency are more important than the chosen style.

Apostrophes in Contractions

A contraction is a shortened form of a word or group of words, using an apostrophe to indicate omitted letters.

Common Contractions

• I am → I’m

• You are → You’re

• He is → He’s

• They are → They’re

• It is → It’s

• Do not → Don’t

• Cannot → Can’t

• Will not → Won’t

• Would have → Would’ve

These are commonly used in informal writing and everyday speech. Avoid contractions in very formal or academic writing.

Important Note: “Its” vs. “It’s”

One of the most frequent mistakes in English writing involves its and it’s.

• It’s = contraction for it is or it has

  • Example: It’s a sunny day.

  • Example: It’s been a long week.

• Its = possessive form of it (no apostrophe)

  • Example: The cat licked its paw.

Rule: If you can replace the word with “it is” or “it has,” use it’s. Otherwise, use its.

Apostrophes and Plurals

Apostrophes are not used to make regular nouns plural.

Incorrect:

• Banana’s are yellow. ❌

• Car’s are fast. ❌

Correct:

• Bananas are yellow. ✅

• Cars are fast. ✅

However, in certain rare cases, an apostrophe can clarify meaning when pluralizing letters, symbols, or numbers.

Examples:

• Mind your p’s and q’s.

• She got straight A’s on her report card.

• There are two 7’s in my phone number.

Although modern style guides often omit the apostrophe (e.g., straight As), adding it is acceptable for clarity.

Possessive Pronouns: No Apostrophes!

Possessive pronouns like his, hers, ours, yours, theirs, its never take apostrophes.

Incorrect:

• The house is her’s. ❌

• The dog wagged it’s tail. ❌

Correct:

• The house is hers. ✅

• The dog wagged its tail. ✅

If a word is already possessive by nature, it doesn’t need another apostrophe.

Apostrophes in Time and Measure Expressions

Apostrophes can also show possession in expressions of time or measure.

Examples:

• A day’s work

• A week’s vacation

• Ten years’ experience

• Five minutes’ walk

In these phrases, the apostrophe shows ownership of time or quantity.
(“Ten years’ experience” means the experience of ten years.)

Special Cases and Style Choices

1. Business Names

Some brand or company names omit apostrophes even when grammatically required.

• Examples: Harrods, Barclays, Starbucks

These are stylistic choices, not grammar rules. You should keep the name as officially written.

2. Possession with Inanimate Objects

Traditionally, some style guides avoided showing possession for inanimate things (like the table’s leg).
However, modern English accepts it:

• The company’s reputation

• The car’s engine

• The city’s skyline

Still, in formal contexts, you can rephrase:
The reputation of the company or the skyline of the city.

Common Apostrophe Mistakes

Understanding these differences helps avoid confusion and makes your writing professional.

Quick Apostrophe Checklist

Before publishing or submitting your writing, ask yourself:

✅ Is the apostrophe showing possession or omission?
✅ Is the noun singular or plural?
✅ Have I accidentally used it to form a plural?
✅ Is “its” or “it’s” being used correctly?
✅ Am I consistent with style (James’s or James’)?

Summary

Apostrophes may be small, but they carry significant meaning. They show possession (the girl’s book, the dogs’ toys) and omission (don’t, it’s, can’t).
Remember these main takeaways:

1. Use ’s for singular possession.

2. Use s’ for plural possession.

3. Never use apostrophes for regular plurals.

4. Distinguish between “its” and “it’s.”

5. Be consistent with style.

Mastering apostrophes not only prevents common grammar errors but also improves clarity, precision, and professionalism in your writing.

FAQs

What is an apostrophe used for in English?

An apostrophe (’) has two primary functions: to show possession and to mark omitted letters in contractions. In possession, it signals ownership or association, as in the teacher’s desk (the desk belonging to the teacher). In contractions, it replaces missing letters, as in don’t (for do not) or it’s (for it is or it has). Importantly, apostrophes are not used to form regular plurals such as apples or cars.

How do I show possession with singular nouns?

For most singular nouns, add ’s to form the possessive, even if the word already ends in s. Examples:

• the dog’s leash
• the boss’s memo
• James’s guitar (also acceptable in some styles: James’ guitar)

Choose a style (always adding ’s or sometimes just an apostrophe after s) and apply it consistently throughout your document.

How do I show possession with regular plural nouns ending in “s”?

When a plural noun already ends in s, place just an apostrophe after the s. Examples:

• the students’ projects (projects of multiple students)
• the teachers’ lounge
• the cars’ engines

Do not add another s after the apostrophe; students’s is incorrect.

How do I show possession with irregular plural nouns?

Irregular plural nouns that do not end in s take ’s. Examples:

• the children’s toys
• the men’s restroom
• the women’s team

Because these plurals lack a final s, they follow the same rule as singular nouns.

What about names that already end in “s” (e.g., Charles, Thomas)?

Both ’s and a lone apostrophe are accepted, depending on your style guide. You may write Charles’s book or Charles’ book. Similarly, Thomas’s hat or Thomas’ hat. Many academic and book-publishing styles prefer ’s; many journalistic styles prefer a lone apostrophe after a final s. Pick a style and remain consistent.

How do I show joint versus separate possession?

Use one ’s after the second name for joint ownership, and ’s after each name for separate ownership.

• Joint possession: Jack and Emma’s apartment (one apartment shared by both)
• Separate possession: Jack’s and Emma’s apartments (two different apartments)

When in doubt, rephrase for clarity: the apartment shared by Jack and Emma.

Do I ever use apostrophes to make plurals?

No for regular nouns. Do not write apple’s to mean more than one apple. However, apostrophes may be used to pluralize single letters, symbols, or occasionally numbers for clarity:

• Mind your p’s and q’s.
• She earned straight A’s.
• There are two 7’s in that code.

Some modern styles omit the apostrophe in these cases (As, Ps), but keep it if removing it could cause confusion.

What is the difference between “it’s” and “its”?

It’s is a contraction for it is or it has. Its is a possessive pronoun meaning “belonging to it.”

• It’s raining. (It is)
• It’s been a long day. (It has)
• The company increased its salary budget. (possessive)

A quick test: If you can replace the word with it is or it has, use it’s. Otherwise, use its.

Which possessive pronouns never take apostrophes?

Possessive pronouns are already possessive, so do not add apostrophes. The most common are: his, hers, its, ours, yours, theirs. Avoid mistakes like her’s or their’s; write hers and theirs instead.

How do apostrophes work with compound nouns and multi-word phrases?

Attach the apostrophe to the end of the compound or the final word in the phrase:

• my brother-in-law’s car
• the editor-in-chief’s decision
• the attorney general’s opinion

For plural compounds, make the main noun plural first, then add the apostrophe: my brothers-in-law’s business.

Are apostrophes appropriate with inanimate objects?

Yes. While older style guides sometimes discouraged using ’s with inanimate objects, modern usage accepts it: the book’s cover, the city’s skyline, the project’s scope. In very formal contexts, you may prefer of-phrases: the cover of the book, the scope of the project. Choose based on tone and readability.

How do I use apostrophes in time and measure expressions?

Use apostrophes to show possessive relationships in fixed expressions of time or measure:

• a day’s work
• a week’s vacation
• five minutes’ walk
• ten years’ experience

Here, the apostrophe signals that the time or measure “owns” or defines the noun that follows.

What are the most common apostrophe errors to avoid?

Watch out for these frequent mistakes:

• Using apostrophes for regular plurals: Write bananas, not banana’s.
• Confusing “it’s” and “its”: Remember, it’s = it is/has; its = possessive.
• Misplaced plural possessives: the Smiths’ house (family name plural + apostrophe), not the Smith’s house if you mean the entire Smith family.
• Inconsistent style for names ending in s: Pick James’s or James’ and keep it consistent.

How do contractions with apostrophes affect tone?

Contractions (e.g., don’t, can’t, won’t, I’m, you’re) generally create a conversational, informal tone suitable for everyday writing, marketing copy, and many forms of digital communication. In academic, legal, or highly formal writing, contractions are often minimized or avoided. Consider your audience and purpose before deciding how often to use them.

How should I handle brand names and official titles that omit apostrophes?

Some brands and institutions choose to omit apostrophes in official names (Harrods, Barclays, Starbucks). Respect the registered form of the name, even if grammar rules would normally suggest an apostrophe. This is a matter of style and trademark, not standard grammar.

Is there a quick checklist I can use to double-check apostrophes?

Yes. Before finalizing your writing, run through this checklist:

• Is the apostrophe marking possession (owner + ’s or plural s + ’) or omission (in contractions)?
• For plural possessives, did I add the apostrophe after the plural s (teachers’ lounge)?
• For irregular plurals, did I use ’s (children’s, women’s)?
• Did I avoid using apostrophes for regular plurals?
• Did I correctly distinguish it’s (it is/has) from its (possessive)?
• Am I consistent with names ending in s (Charles’s vs Charles’)?

Can you provide a few sentence-level examples that combine these rules?

Certainly:

• The committee’s decision will affect the employees’ schedules next week.
• It’s clear the company expanded its footprint over the last ten years’ growth cycle.
• My sister-in-law’s start-up just hired two designers.
• Jack and Emma’s plan conflicts with Thomas’s proposal, but they’re revising it.
• Please dot your i’s and cross your t’s in the final draft.

Use these as models to check possessive placement, pronoun usage, and tone with contractions.

English Grammar Guide: Complete Rules, Examples, and Tips for All Levels