The Ballast is one of the basic requirements needed for fluorescent lamps to operate. Any fluorescent lamp needs an initial kick to start. The initial kick is provided in the form of high voltage by the ballast. Ballasts are devices intended to limit the amount of current in an electric circuit. There are two basic functions for ballasts. One is providing the starting kick and the second is to limit the current to the proper value for the tube you are using.
Without these functions, no fluorescent lamp can work properly. The ballast provides a high initial voltage to initiate the discharge, and then rapidly limits the lamp current to safely sustain the discharge. Lamp manufacturers specify lamp electrical input characteristics (lamp current, starting voltage, current crest factor, etc.) required to achieve rated lamp life and lumen output specifications. Ballasts must generally be closely matched to the lamp in terms of tube wattage, length, and diameter.