Hi Jaguar- The logic of a moving average crossover is that if you can see a change in direction in the short term moving average, then we can most likely catch the beginning of a wave. But you simply can't take every trade when an EMA moves up and down. You'd be making hundreds of trades a day and would probably lose almost all the time. In order to prevent fakeouts, you add a filter (a longer term moving average). The longer term moving average gives you an idea of what the bigger trend is. Now if you see the shorter moving average crossover the longer moving average, you have a good indication that a trend change might be occuring. If you don't have a crossover, then you know not to enter because the price may just be making a short term retracement. Hope that helps! Happy trading!