First the jackpot is "seeded" with a base start-amount. Then each time any player anywhere on earth takes a spin or bet on the progressive casino game (a specific slot machine, or poker game), a small portion of cash is taken and added to the Jackpot, increasing how much can be won. The jackpot usually triggers randomly, quite often lavishing winners with life-changing sums of cash. Jackpots on progressive casino games have been known to reach over $15,000,000.