The apostrophe is an element of punctuation and a diacritical mark.
This is the symbol used to indicate an apostrophe: ‘
- It’s (it is) a nice day outside.
- You aren’t (are not) supposed to be here.
- Who’s (who is) at the door?
We use apostrophe in contractions of verbs to:
- create the negative in abbreviated form
- set together the subject (usually a pronoun) with the verb.
External link to Apostrophe in verbs exercises (1169).