What is a forecast?
A forecast is your best estimate of how much revenue you can generate in a defined forecast period. This amount made up of Commit Amount - the amount you are confident to realize - and Best Case Amount - the total amount of revenue you might possibly generate.

Customizable forecasting is a flexible solution for estimating how much revenue your organization can generate or how many products your organization can sell. You can set up customizable forecasting in order to reflect how your organization forecasts its revenues. Applying this functionality, you can forecast on a monthly or quarterly basis, use different dates when applying amounts to forecasts, forecast based on revenue or quantity or both, and define additional quotas based on product families.

The Forecast Category determines the category to which an opportunity is assigned in a forecast. The default category setting for an opportunity is associated to its stage, as set in the Stage picklist. To update the Forecast Category for a particular opportunity, you must edit that opportunity’s forecast.

The following Forecast Categories exist:
 

• Pipeline: This is the sum of all your open opportunities in a forecast period.
• Best Case: The total amount that you could bring in if all the stars aligned in the period. The Best Case amount is the total of opportunities that are categorized as Closed, Commit and Best Case.
• Closed: The total amount of the opportunities you've won in a forecast period.
• Commit: Commit is the amount that you confidently believe you can generate in a forecast period. The Commit category is made up of closed opportunities plus those opportunities that you're committing to win.
• Omitted: This category is made up of opportunities that you lost or that you want to omit from the forecast. For example, you might want to omit an opportunity from your forecast if your buyer informs you that the budget for the opportunity has just been cut.

Forecast categories can automatically be assigned to sales stages. As you update the stages to your opportunities, Salesforce makes corresponding changes to associated forecast categories. Here is an example that shows the different use of the forecast categories 'Pipeline' and 'Omitted'.

Example	Sales Stage	Type	Probability	Forecast Category
#1	Negotiation/Review	Open	90%	Pipeline
#2	Won	Closed	100%	Closed
#3	Lost	Closed	0%	Omitted