What is policy routing
Policy routing in pfSense refers to the capability of routing traffic by matching it to specific firewall rules. Each firewall rule allows selection of a gateway. If none is selected, traffic goes out the default gatway or follows the routing table. If additional WAN interfaces (OPT WAN) or gateway groups are defined, these may be selected in the Gateway field when adding or editing rules to direct matching traffic as desired. This is primary used for multi-WAN, though it has other uses as well.