Walk me through how Forecasting works in Salesforce.

Collaborative Forecasts (the modern Salesforce forecasting feature) lets sales teams predict revenue by quarter (or month) and roll predictions up the role hierarchy. It is heavily configurable and admin-owned.

Key concepts:

• Forecast Type — a configured forecasting flavour: which object (Opportunity, Opportunity Splits, Custom Forecast Object), which date field, which currency or quantity measure, and which user role. You can have multiple Forecast Types active (e.g., Revenue, ARR, License Quantity).
• Forecast Categories — the 5 standard buckets (Pipeline, Best Case, Commit, Closed, Omitted) that map to Opportunity Stages. The mapping is configured per stage.
• Rollup mechanism — each user's forecast is the sum (or other measure) of their owned Opportunities in each category. Managers see their reps' forecasts plus their own override at each level.
• Quotas — admins set quarterly or monthly quotas per user. The forecast is then displayed as % attainment vs quota.
• Adjustments — managers can adjust their reps' rolled-up numbers (e.g., "Bob's pipeline says $1M but I think $800K is realistic"). Adjustments don't change the underlying opportunity data; they only change the displayed forecast.

Setup:

1. Enable Collaborative Forecasts in Setup.
2. Configure Forecast Types — pick measure, date, role.
3. Map Stages to Forecast Categories.
4. Build the role hierarchy used for the rollup (Forecasts uses the standard role hierarchy, but you can override with custom Forecast Hierarchy if needed).
5. Set Quotas (per user, per period — uploadable via Data Loader).
6. Enable for users via Permission Set Licence + Forecast User permission.

Common gotchas:

• Quotas don't roll up automatically — you set them at every level individually, or use the API to load them.
• Custom Opportunity fields can be added to forecast types but only certain field types (currency, number).
• Splits — Opportunity Splits add complexity; each split owner gets their portion in their forecast.

Forecasting is one of the more configuration-heavy features, and it's frequently the most-customised area in any sales org.