Answer:
Forecasting is a very important step in the planning process, so much that without forecasting, the planning process for a project of a firm as a whole would not be possible.
Step-by-step explanation:
The reason is that by definition, planning corresponds to a process that will be realized at some point in the future, (whether in the long or short-term depends on the planning horizon), and for the most part, information about the future is uncertain, and hard to predict. For that reason, the planning process must use forecasting methods to determine important variables like future sales, future revenue, future costs, and so on.
There are many forecasting techniques. For the most part, these techniques are statistical in nature and based on past information that is supposed to replicate somehow in the future. However, sometimes, more qualitative or intuitive forecasting methods are used, when statistical information is hard to come by.