ZN

If you inflate the balloon manually, it will not be able to take off, because you will fill it with nitrogen. Nitrogen is heavier than air, so the balloons won't fly.

To make the balloon fly, it is filled with helium. Helium is lighter than air, so balloons filled with helium rush upward.

So that the balls do not fly away to the ceiling, but remain in a visible place, they are tied to various objects. Quite often I see them tied to inflated balloons, which are simply filled with cereals, water, or small objects.

By the way, my younger sister and I used to kick holiday balloons at each other like soccer balls when we were kids. The main goal of the game was to keep the ball from touching the floor.