Dependent picklists and controlling fields
Key Takeaway
A dependent picklist's valid values depend on the value of a controlling field. Converting existing fields into a dependent picklist or controlling field does not change the values already stored in records.
A dependent picklist is a picklist whose list of valid values changes based on the value of another field, called the controlling field. The controlling field must be on the same record. App builders use this pairing to help users enter accurate and consistent data.
Example of a dependent picklist
For example, imagine a custom Reason picklist on opportunities that depends on the Stage picklist. When Stage is Closed Won, Reason offers only win reasons: Superior features or Lower price. When Stage is Closed Lost, Reason offers Inferior features, Higher price, or Company viability.