Explanation
Two functions that an administrator should use when creating a validation rule are:
Error condition formula, which defines when an error should occur based on record fields and values Error message location, which specifies where on the page layout an error message should appear when triggered by an error condition formula Formula return type and rule active date are not functions used for validation rules. References:
https://help.salesforce.com/s/articleView?id=sf.validation_rules_overview.htm&type=5

Section: Volume B

Explanation/Reference: Except for case comment and Email message records you can create a field update action that updates a field on the related case record. For e.g. You can create a rule to change the status of a case from " Awaiting Customer Response " to "In Progress" when a customer adds a case comment.