Everyone try to forecast the future. Bankers need to predict credit worthiness of customers. Marketing analyst want to predict future sales. Economists want to predict economic cycles. And everybody wants to know whether the stock market will be up or down tomorrow. Over the years, many software have been developed for this purpose and one such software is the neural network based forecasting application. No, neural network is NOT a medical term. It is actually a branch of artificial intelligence which gains much prominence since the start of the millenium. NN or neural network is a computer software (and possibly hardware) that simulates a simple model of neural cells in humans. The purpose of this simulation is to acquire the intelligent features of these cells. In this book, when terms like neuron, neural network, learning, or experience are mentioned, it should be understood that we are using them only in the context of a NN as computer system. NN have the ability to learn by example, e.g. a NN can be trained to recognize the image of car by showing it many examples of a car or to predict future stock prices by feeding it historical stock prices.