Labouchere

The Labouchere system is also known as the cancelation system. You start by writing down a sequence of 3 or more numbers they can be anything you like 1 - 2 - 3 - 4, 2 - 2 - 5 - 3 - 1 or all the same 1 - 1 - 1 - 1. These numbers represent an amount of units for you to bet.
For this example i will use 2 - 1 - 2 - 3 - 1.

To begin the sequence you add the two outside numbers (2+1=3) and bet that amount (3 units). If you win you cross off those numbers from the sequence 1 - 2 - 3 and add the new outside numbers for your next bet (1+3=4). If you loose you add the amount bet (3 units) to the end of the sequence (2 - 1 - 2 - 3 - 1 - 3) and again add the two outside numbers for your next bet and so on.
The sequence is completed once you have crossed off all your numbers

Like Martingale this system has been discredited and I havent personally used it to comment.