people is the plural of person.
However, 'persons' is used in official language like 'maximum 8 persons' in a lift/elevator, or 'persons of interest' by the police. It is NOT used in normal conversation. NOBODY says 'there were 10 persons at my barbeque' That's totally strange!
a 'person' is also a legal term, meaning not you, the human, but the legal you, where your name is in capital letters on all legal documents.. although most people don't find out anything about the law.