Project functional libraries

How many functional libraries can we have in a project?

We can create all the functions in one function library and we can use that one.
But in some projects people create multiple number of function libraries.Could any one of you plz explain on what basis they differentiate function libraries from each other.

thanks in advance

I generally keep similar functions in one function library. For example, in my automation framework, I have DP Objects in one library, all Global functions in one and Reusable actions (Login script, finding an object etc.) in one. So, my entire framework is made up of three function libraries.

You can have as many as you want, but having too much would cause confusion, don't you think?