Progressive jackpots take a small portion of each player's bet, adding it to the jackpot prize. Hence, the more people playing a progressive jackpot, the quicker it grows. However, this also means more people competing for a single prize pot, which is why some experts advise playing smaller, less busy progressives. Be aware that if you plan on playing a progressive jackpot slot, it's essential to read the rules beforehand. Some have specific rules such as; only players using max bet can play for the jackpot, or bet size correlates with the probability of hitting a jackpot prize.