These are dots. They come in all shapes, sizes, and colours.
At the center of each dot, there is a light. The light shines out from big holes in their shiny skin.
Dots live on light. Because their skin is so shiny, most dots are often fooled by their own reflection when around other dots.
Some dots are blurry. Because they don't reflect light, and sometimes don't shine in the direction of other dots, the blurry ones often have a hard time, because they are boring.
When a dot tries to close the distance between itself and another dot too quickly, the other dot might turn blurry. Otherwise, an unwanted new dot might get made, or the smaller of the dots might die.
A new dot is made usually when two opposite big dots shine hard enough at each other, and then collide. Really, though, the only thing that makes a new dot is a collision.