Rules enable you to manipulate the list of recommended product IDs before passing the list to the storefront at run time.
Note You aren’t required to define rules, and it's common for configured recommenders to
not use any rules. If you choose to not use rules, all of the product IDs in the list
are sent to the storefront in the exact order in which the strategy (or strategies)
returned them.
Create and apply up to 30 rules for any given recommender. Each rule specifies an action, a field, and one or more field values (or attributes).
When B2C Commerce Einstein applies a rule, it checks each product in the list of IDs returned by the strategy (or strategies), and compares the product's field value to the values specified in the rule. If the product's field value matches the specified field value in the rule―or matches one of the specified values in the rule if there are more than one―the action applies.