A master-detail relationship is a parent-child relationship in which the master object controls certain behaviors of the detail object. The master object can be a standard or custom object, but not all standard objects support being a master. Roll-up summaries are fields that calculate the sum, count, min, or max of child records. The owner field on the detail records is not available and is automatically set to the owner of the master record.
References: https://www.forcetalks.com/blog/master-detail-relationship-in-salesforce/ https://help.salesforce.
com/s/articleView?id=sf.fields_about_roll_up_summary_fields.htm&type=5