Portfolio: How are items assigned in the capacity view? To sprints/ teams/ people?

[Jeroen Thoelen]

Hi, 

When I go to the team capacity view, I see that teams/ people / sprints are automatically assigned with items. Is that correct? Or what if I don't assign an item to a specific person, does portfolio assign it to someone as early as possible where there is some capacity free? 

And regarding to sprints, does portfolio also assign items automatically to them in the capacity view, as early as there is some free space? 

I have some difficulties to understand how Portfolio does this. 

Thank you.