Monte Carlo Simulation, also known as the Monte Carlo Method or a multiple probability simulation, is a mathematical technique, which is used to estimate the possible outcomes of an uncertain even. In simple words, mcs using random numbers to simulate events and under law of large number , the out come of prediction will similar to what happens in reality in theory. The model using in this indicator is geometric Brownian motion , basic equation of GBM is Delta price=price(drift x dt + sigma x dW) Drift is similar to 'trend' and W is a random variable,sigma is volatility of price. It's interesting that how the simulated price touch those trend line or resistance/support.