Grids, like the Honl grid attached to my flash here, are very important modifiers. A grid ensures that the light from a flash does not go “everywhere”. Instead, it goes to one cone of light, that drops off softly at the edges. This was taken by a student a few hours ago:
Oddly, that cone is a bit softer than the straight flash.
TIP: Use a gel if you want to see where a light is going, That way you can identify easily which light is shining where:
And have fun.