Apostrophe to show two words have been connected (contraction)
We sometimes connect two words to make one shorter word. We use an apostrophe to show that we have left out one or more letters:
do not → don’t
it is → it’s
is not → isn’t
you have → you’ve
cannot → can’t
will not → won’t
wh-word + ’s, ’d, etc.
We use ’s for has and is:
She’s seen that movie already. (has)
He’s my brother. (is)
We use ’d for had and would:
They’d never been to Japan before. (had)
She’d love to live in the USA. (would)
Apostrophe + s to show possession
When we show who owns something or has a close relationship with something, we use an apostrophe + s after the name or the noun. When the noun is plural, we put the apostrophe after the s:
Is that Frank’s camera?
There was a big teachers’ conference last week in Mexico City. (a conference for teachers)
Apostrophe with time
We can use an apostrophe + s to show duration. When the time noun is plural, the apostrophe comes after the s:
For me, writing an essay involves at least an hour’s work.
It was just ten minutes’ walk from my house to my office. (the walk from my house to my office takes just ten minutes)
When we write the time, we sometimes use o’clock:
14:00: two o’clock
18:00: six o’clock
Apostrophe: typical error
We use an apostrophe to contract it is to it’s. We don’t use an apostrophe with possessive its:
The University is very proud of its gardens.
of it’s gardens.