Light Modifiers
Light modifiers change the properties of a light source, such as its size, shape, diffusion, colour or beam angle. This can help achieve certain looks, like soft shadows or dramatic spotlights, with no limit to the creative potential on offer as various modifiers are used.
As a general rule, the larger the modifier, the softer the light will become. While bare bulb flash can be useful in certain situations, you are extremely limited to the looks you can create with a flash by itself.