mine, yours, his, hers, ours, theirs

A possessive pronoun says who something belongs to, without the noun after it. It saves you saying the noun twice.

Its has no pronoun form here.

My or mine

My, your, her go before a noun. Mine, yours, hers stand alone, with no noun after them.

Whose

Ask about the owner with whose. The answer often uses a possessive pronoun.

A friend of mine

a + noun + of mine means "one of my …". You can't say a my friend.

Common mistakes

The pronouns have no apostrophe, and mine has no -s.

• × This book is your's. → This book is yours.
• × The house is their's. → The house is theirs.
• × That bag is mines. → That bag is mine.
• × a my friend → a friend of mine
• × That's mine phone. → That's my phone.