Explain Opportunity stages, close date, probability, and forecast category relationships.

Each Opportunity Stage picklist value has three attributes configured in Setup:

1. Probability (%): The default win probability for that stage — Salesforce auto-populates this on the Opportunity when the stage changes, but reps can override it manually.
2. Forecast Category: Maps the stage to a forecasting bucket — Pipeline, Best Case, Commit, Omitted, or Closed. This determines whether the opportunity appears in collaborative forecasting totals.
3. Close Date: Required field; the expected close date drives pipeline aging reports and forecast periods. Best practice is to align stage names to real buyer milestones (Discovery, Proposal, Negotiation, Closed Won/Lost) so probability reflects actual win likelihood. Admins can create multiple Opportunity record types with different stage picklists to support different sales motions (e.g., New Business vs Renewal).