What they all attempt to do is give the player more paths to a win and fewer paths to a loss. They are generally designed to trade off a number of paths to small losses for a few paths to large gains.

Progressive Betting – Different Types
There are many different types of betting systems. For the purpose of this mini-course, I will not go into detail on how each works, or discuss their relative advantages and disadvantages. I will, however, point out the two different types of systems:
Increase as You Lose Systems
With this type of betting system, you increase the amount of your bet each time you lose a hand. Example: Bet one unit, lose, bet two units, lose, bet three units win, bet one unit. In this progression, the player increases his bet after every loss and returns to his original bet after a win.
Increase as You Win Systems
With this type of betting system, you increase your bet after every win. Example: Bet one unit, win, bet two units, win, bet three units, win, bet four units, lose, bet one unit. In this progression, the player increases his bet after every win and returns to his original bet after a loss.
Each system has advantages and disadvantages. The “Increase as You Lose Systems” have the advantage that after you have won a hand, you will have recouped all your losses and will be up one betting unit. The disadvantage of this system is if you encounter a long losing streak, your bet will escalate to impossible levels. Consider for instance a system where you start off with a $10 bet and double it every time you lose Bet $10, lose, bet $20, lose, bet $40, lose.
A losing streak of 7 or 8 hands (which is not uncommon by any means) can result in losses in the thousands starting off with just a $10 bet. In my opinion, this is an unacceptable risk given the potential payoff of one unit ($10 in the above example). These systems have a tremendously high risk of ruin.
The “Increase as You Win Systems” has the following advantages. First, you are only increasing your bet when you win. You are essentially playing with the Casino’s money at that point and not putting your hard-earned cash at risk. Instead, you only raise your bet when you have actually taken money from the Casino with a prior winning hand. Second, at the end of a long winning streak, you will have won a great deal of money. Consider the following progression: Bet $10, win, Bet $20, win, Bet $30, win, Bet $40, win, bet $50, lose. This progression will have won $60 in total after only 4 winning hands and one loss. A flat-line betting of $10 per hand would have only won $50. For even longer streaks, the potential winnings are incredible. The disadvantage of this type of system is that during periods where you are trading wins and losses with the dealer, you will lose more money than if you were flat betting each time.