1. Când te referi la it is sau it has, foloseşti apostroful.
It’s a nice day. (It is)
It’s your right to refuse the invitation. (It is)
It’s been great getting to know you. (It has)
2. Când vrei să exprimi posesia foloseşti its, fără apostrof.
The cat hurt its paw.
The furniture store celebrated its tenth anniversary.