What are Roll-Up Summary fields?

A roll-up summary field calculates values from related records, such as those in a linked list. The roll-up summary is a gathering calculation that pulls information from several areas. You field to display a value in a master record based on the values in a detailed record. The detail record must be related to master through a master-detail relationship.

You can execute different calculations with roll-up summary fields. You can count the how many detail records related to a master record. Roll up summary fields and fields are always read-only on detail pages and are available on edit pages. You can create a roll-up summary field to display a value in a master record based on the values of fields in a detailed record.