"A firewall object is designed to represent a real firewall device in your network. This firewall object will have interface and IP address objects that mirror the real interfaces and IP addresses of the actual device. In addition, the firewall object is where you create the access policy rule sets, NAT rule sets, and routing rule sets that you assign to your firewall device.
"By default, a firewall has one Policy rule set, one NAT rule set, and one routing rule set. However, you can create more than one rule set using branching rules (for firewalls that support them). On the other hand, you don’t have to populate all the rule sets. You can, for example, create a Policy ruleset and leave the NAT and Routing rule sets empty. We explains more about policies and rule sets below."
