ACTUALS:  expressed customer demand (what the customer actually wants and orders).

FORECAST:  a reasonable estimate of sales attainable under a given set of conditions (what is likely to happen).  Two particular types of forecasts are the volume forecast and the mix forecast.

PLAN:  a sales volume expectation and planned response in order to meet company objectives (what management wants to happen).  Consider the following types of planning:

Demand Plan:  a planned company response to the demand forecast.

Financial Plan:  an expectation of what sales volume and/or revenue must be to meet company financial objectives.

Production Plan:  the schedule of operational activities to meet the demand plan.

FORECASTING LEVEL:  the focal point in the corporate hierarchy where the forecast is needed.

FORECASTING TIME HORIZON:  the time frame for how far out one should forecast.

FORECASTING TIME INTERVAL:  how often the forecast is updated.

POTENTIAL ESTIMATE:  the maximum estimate attainable under a given set of conditions.  With new product forecasting, it is important to distinguish a potential estimate from a forecast.