Writing LexFizz Team 9 min read
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Key Takeaways
  • The apostrophe has two jobs: showing possession and marking contractions.
  • Singular possession adds 's; plural nouns ending in -s add just an apostrophe.
  • Contractions use an apostrophe to mark missing letters: do not → don't.
  • Its (possessive) has no apostrophe; it's means it is or it has.
  • Never use an apostrophe to make an ordinary plural (apples, not apple's).

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The apostrophe is a tiny mark that causes outsized confusion — even for native speakers. It does only two jobs in English: it shows possession and it marks contractions. Almost every apostrophe error comes from misunderstanding these two functions, or from adding an apostrophe to a plain plural where none belongs. This guide lays out every rule clearly, with tables and examples, and tackles the notorious its vs it's problem head-on.

The Two Jobs of the Apostrophe

An apostrophe (') does only two things in standard English:

  • Possession: it shows that something belongs to someone — Sara's book.
  • Contraction: it marks one or more missing letters — can't (cannot), I'm (I am).

If a word with an apostrophe is doing neither of these, the apostrophe is almost certainly wrong.

Why it matters: Apostrophe errors are highly visible and instantly mark writing as careless, even when the rest is excellent.

Possession: Singular Nouns

To show that something belongs to a single owner, add 's — even if the noun already ends in -s.

Singular Possession

OwnerPossessive
the dogthe dog's bone
my friendmy friend's car
JamesJames's house (or James' house)
the companythe company's profits

With names already ending in -s, both James's and James' are accepted; choose one style and stay consistent.

Possession: Plural Nouns

For plural nouns that already end in -s, add only an apostrophe after the s. For irregular plurals that do not end in -s, add 's as normal.

Plural Possession

Plural nounPossessive
the dogs (plural, -s)the dogs' bones
the students (plural, -s)the students' results
the children (irregular)the children's toys
the women (irregular)the women's team
Pro tip: Ask "is the owner singular or plural?" first. The dog's bones = one dog; the dogs' bones = several dogs.

Contractions

A contraction joins two words and uses an apostrophe to mark the missing letters.

Common Contractions

Full formContraction
do notdon't
I amI'm
she willshe'll
they arethey're
would havewould've

Contractions are normal in speech and informal writing but are usually avoided in formal academic writing.

Its vs It's

This is the single most common apostrophe error in English. The rule is simple but counter-intuitive:

  • its (no apostrophe) = possessive: The cat licked its paw.
  • it's (with apostrophe) = it is or it has: It's raining. / It's been a long day.

Its behaves like other possessive pronouns — his, hers, ours, theirs — none of which take an apostrophe. The test: if you can replace it with it is, use it's; otherwise use its.

When NOT to Use an Apostrophe

Do not use an apostrophe to make an ordinary plural. This error — sometimes called the "grocer's apostrophe" — appears on signs everywhere.

Correct: apples, tomatoes, the 1990s, three DVDs

Wrong: apple's, tomato's, the 1990's, three DVD's

Also, possessive pronouns (yours, hers, ours, theirs, its, whose) never take an apostrophe.

Common Mistakes

The top errors are: confusing its and it's; adding apostrophes to plain plurals; misplacing the apostrophe in plural possessives (the student's results when you mean many students); and putting an apostrophe in possessive pronouns (your's is never correct). When unsure, ask whether the word shows possession or marks missing letters — if neither, drop the apostrophe.

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Related Articles

WRITING English Punctuation Guide GRAMMAR English Possessives Explained GRAMMAR English Contractions Guide

Frequently Asked Questions

What are the two main uses of the apostrophe?
The apostrophe shows possession (Sara's book) and marks contractions where letters are missing (don't = do not). These are its only two standard jobs in English. If a word has an apostrophe but is doing neither of these, the apostrophe is almost certainly an error.
How do I show possession with a singular noun?
Add 's to the owner, even if it already ends in -s: the dog's bone, my friend's car, the company's profits. With names ending in -s, such as James, both James's and James' are accepted — just choose one style and use it consistently.
How do I show possession with a plural noun?
If the plural already ends in -s, add only an apostrophe after it: the dogs' bones, the students' results. If the plural is irregular and does not end in -s, add 's as usual: the children's toys, the women's team.
What is the difference between its and it's?
Its (no apostrophe) is possessive: "The cat licked its paw." It's (with apostrophe) means "it is" or "it has": "It's raining." The test is to expand it: if "it is" fits, use it's; otherwise use its. Possessive pronouns never take an apostrophe.
Should I use an apostrophe to make a plural?
No. Ordinary plurals never take an apostrophe: apples, tomatoes, the 1990s, three DVDs. Adding one — apple's, DVD's — is a common error sometimes called the grocer's apostrophe. Use the apostrophe only for possession or contractions, never for plain plurals.
How do contractions use the apostrophe?
A contraction joins two words and uses an apostrophe to mark the missing letters: do not → don't, I am → I'm, they are → they're, would have → would've. The apostrophe goes exactly where the letters were removed.
Do possessive pronouns take an apostrophe?
No. Possessive pronouns — yours, hers, ours, theirs, its and whose — never take an apostrophe. So "the book is yours" is correct, while "your's" is always wrong. This is one of the most frequent apostrophe mistakes in English writing.
How do I write the possessive of a name ending in s?
Both forms are accepted: James's house and James' house. Modern style guides often prefer adding 's (James's) because it reflects how the word is spoken, but the apostrophe-only form is also correct. The key is to choose one approach and apply it consistently.
Are contractions acceptable in formal writing?
Contractions are normal in speech and informal or semi-formal writing, but they are usually avoided in formal academic writing, where full forms like "do not" and "cannot" are preferred. In emails, blogs and everyday writing, contractions are perfectly appropriate.
How can I practise apostrophe rules?
Rewrite sentences turning phrases into possessives and contractions, and proofread text to spot misplaced apostrophes, especially its vs it's and plural errors. LexFizz's Grammar Quiz and Complete the Sentence exercises give free, focused practice.