In the Martingale each bet is doubled after a loss, and you go back to your starting bet after every win. You will win one unit for every win, as long as you have enough money and do not get to the house limit. Once you reach the house limit, then you will lose the house percentage because there is no place else to go.
There are many variations of Martingale, and it can be used with other methods.
For example, you can use a three-stage Martingale of 10-20-40 combined with betting that the decision before the last one will repeat.... Or bet that the
FIRST shooter (only) will throw a pass (or don't pass). In this latter one you are betting only one bet on each shooter.
Some people add one or more units to each of the doubled bets. Others will change to a parlay after a certain point (let the first bet "ride" on the second bet after a win) and bet the amount that it takes to win what you want to win. Another variation would be to split it up and then win it back one part at a time.... There are many variations of Martingale with which people swear they are winning.