A criteria-based sharing rule is a tool that allows administrators to share records with certain users based on field values rather than ownership. For example, a criteria-based sharing rule can share all opportunities with a cross-sell opportunity type with a specific group of users. A public group is a collection of individual users, roles, roles and subordinates, or other groups that can be used to simplify sharing settings and other processes. In this case, the administrator can add the subject matter experts to a public group and give them access to records with a criteria-based sharing rule that matches the cross-sell opportunity type. Reference: https://help.salesforce.com/s/articleView?id=sf.sharing_criteria_rules.htm&type=5 https://help.salesforce.com/s/articleView?id=sf.public_groups.htm&type=5