The D'Alembert roulette system is a betting strategy that involves increasing bets after a loss and decreasing after a win, focusing on even chance bets. It was created by a French mathematician and is designed to keep you one step ahead of the casino. Even when winning and losing an equal number of bets, you can still make money. It's particularly effective on French roulette tables that offer half your money back when the ball lands on zero. The strategy is rated highly because it can turn a break-even session into a winning one and offers a systematic approach to betting.