Lightning has been observed associated with over 200 volcanic eruptions at more than 80 volcanoes. Here we use a global observational database together with modern instrumental data to explore the systematics of volcanic lightning. We find that lightning occurs in three regimes: 1) vent discharges, short pulses when explosions are in progress; 2) near-vent lightning, km scale, directly above the vent; and 3) plume lightning, larger scale lightning very similar to thunderstorms. The role of water and ice in volcanic lightning will be highlighted.