‘It’s’ and ‘its’ are short words that are easy to use incorrectly. Here are 2 rules to help you.

Rule 1: write ‘it’s’ when you mean ‘it is’

‘It’s’ is always a grammatical contraction of ‘it is’. A grammatical contraction is when we bring 2 words together to make a shorter word by removing a letter or 2. An apostrophe replaces the missing letters – ‘I’ll’ for ‘I will’ and so on.

While ‘it’s’ and ‘it is’ mean the same, writing ‘it is’ gives your writing a formal tone.

Rule 2: write ‘its’ for the possessive form of the pronoun ‘it’ 

Pronouns stand in for nouns. Here, the pronoun ‘it’ stands in for the noun ‘rabbit’. Because the ‘it’ (rabbit) possesses something (cage), we use the possessive form ‘its’.

If we enjoyed repetition, we’d write: ‘Put the rabbit back in the rabbit’s cage.’

Like ‘rabbit’s’, nouns use an apostrophe to show they possess what follows. But pronouns like the possessive ‘its’ (e.g. my, our, yours, theirs) never have an apostrophe.

Simple trick

If you don’t mean ‘it is’, write ‘its’.

Style Manual pages

• Apostrophes
• Pronouns