The ballasts starter takes the signal from the vehicle and quickly sends it to the ballast. The ballast then amplifies the signal to a high current signal and sends it to the bulb. The HID bulb receives the signal and creates the light. The bulb is filled with a mixture of gases and salts. When the bulb receives the amplified power from the ballast, it energizes the gases in the bulb creating a white/blue light output. The color varies, depending on the Kelvin (K)/color temperature of the kit.