Question: I know pretty well that the plural for 'person' is 'people'. But my literature professor used once the word 'persons' because, he said, he was using the word the same as it will be used 'individuals'. Or at least I understood it that way. 

So, my question is: Can I use the word 'persons' in the next phrase? (I wrote the whole phrase in order for you to have the correct context.)

> 
> I'm so into the idea of developing each skill alike, the idea of being
>  round **persons**.
> 
> 
> 

Is it okay, or should I just use 'individuals'?

Thank you! :)

Answer: 
In general, the plural of "person" is "people". Exceptions include formal contexts such as law enforcement, and idiomatic phrases like "missing persons" or "persons unknown".

A historical prescription is to use "people" for an unspecified number of people, and "persons" for a specific number of individuals: "many people" but "three persons". However, this rule is no longer followed, and "people" is used for both cases.

In your example, I would use "people". (I would also suggest using "well-rounded" instead of "round", and using a more articulate phrase than "so into" to describe your interest.)

Sources:

* [Grammar Girl: People or Persons?](http://www.quickanddirtytips.com/education/grammar/people-or-persons)
* [Daily Writing Tips: People versus Persons](http://www.dailywritingtips.com/people-versus-persons/)
* [Grammarist: People vs. persons](http://grammarist.com/usage/people-persons/)
Your sentence doesn't quite make sense and I think you need to use "individuals" if you want to refer to more than one person.

You could say:

> 
> I'm so into the idea of developing each skill alike, the idea of being
>  a rounded person.
> 
> 
> 

or

> 
> I'm so into the idea of developing each skill alike, the idea of having
>  rounded individuals. 
> 
> 
> 

You can't really use "being" with "rounded individuals" as you can't "be" more than one person.

Also, you don't say what audience this is meant for.

"I'm so into" is a very "hip" was of saying "I am very enthusiastic about". For a more formal situation you probably should use the latter.