There are three main types of forecasting methods: qualitative, extrapolative, and causal. Qualitative methods rely on expert opinions and are useful for medium to long range forecasting. Extrapolative methods use past historical demand data to identify patterns and extrapolate them into the future. Causal methods use statistical models based on historical demand data and other variables that influence demand. Some specific forecasting techniques mentioned include the Delphi technique, market surveys, scenario writing, moving averages, weighted moving averages, exponential smoothing, regression analysis, and econometric methods.