The D'Alembert betting system is a gambling strategy primarily used in games of chance, such as roulette. It is based on the idea of balancing winning and losing bets. The approach involves adjusting the bet size incrementally; after a loss, the player increases their bet by a set amount (usually one unit), while after a win, the player decreases the bet by the same fixed amount. The goal is to recover losses gradually by capitalizing on winning streaks while managing risk during losing streaks.