This very simple money management system is most commonly used at the horse track. When betting on horses, you make your wager, if you win your bet, you reinvest (hence the name parlay) the money you won on your next wager. When you do this you are also doing a let it ride wager.
The Parlay System is not necessarily void of any types of risks, but it does provide the smallest amount of risks of all the bets. Actually, the bettor is only concerned with a win, place, or show variety or a combo of these three.
Like the Martingale System, this money management system has been around since dirt was craeted.