42b Use apostrophes in contractions.
Contractions are two-word combinations formed by leaving out certain letters, which are indicated by an apostrophe.
| it is, it has/it’s | I would, I had/I’d | will not/won’t |
| was not/wasn’t | he would, he had/he’d | let us/let’s |
| I am/I’m | would not/wouldn’t | cannot/can’t |
| he is, he has/he’s | do not/don’t | who is, who |
| you will/you’ll | does not/doesn’t | has/who’s |
Contractions are common in conversation and informal writing. Academic and professional work, however, often calls for greater formality.
Distinguishing it’s and its
Its is the possessive form of it. It’s is a contraction for it is or it has.
This disease is unusual; its symptoms vary from person to person.
It’s a difficult disease to diagnose.