What are the apps of power factor correction

Power factor correction for a bank of ballast operated fluorescent bulbs or group of induction motors could be done by fixing a single capacitor to each lamp/motor or at the main switchboard by an automatic pfc capacitor bank by sensing pf and switching on capacitors in steps. Alternatively each motor rated more than 4kW could be fitted with a pfc capacitor. Sometimes a synchronous motor connected to the main switchboard is used to correct the pf. Each method has its advantages/disadvantages.