Most of the time, people is the correct word to choose as a plural for person. Persons is archaic, and it is safe to avoid using it, except in legal writing, which has its own traditional language. Peoples is only necessary when you refer to distinct ethnic groups (for example, within the same region).

The answer is that technically speaking, it’s not wrong. But people has become the more common word to use when referring to person in the plural form. In fact, some style guides explicitly state not to use the word persons.

If you are referring to one individual, that individual is a person. If you are referring to two or more individuals, those individuals are people. You can remember this rule by noticing the ON at the end of person, and the ON at the beginning of one. This should help you remember that a person is one individual.

The use of the word “persons” isn’t too popular anymore, though, as references like the AP Stylebook and The New York Times recommend only using “persons” if it’s in a direct quote or part of a title (e.g., Bureau of Missing Persons). Your best bet is to say, Mark was one of the most generous people I’ve ever met.

Both persons and people are what we call collective nouns, and both are the plural forms of the singular noun person. Wait, they’re both the correct term? Yes and no. Let me explain. The word people is the most common and de facto plural form, but persons is also grammatically correct, just used less frequently and in more specific contexts.