Security zones

Gateway security devices, such as firewalls, define security zones to apply security policies to incoming and outgoing network traffic. To put this in a different way, a security zone is a logical structure that's created from one or more device ports/interfaces that apply the same security policies. A security zone can be just one interface, or it can include several interfaces if the interfaces apply the same policies. Each interface may also be a security zone, and a security zone may also include two or more interfaces. However, an interface can belong to only one security zone.

Firewall zones

Many firewalls (hardware or software) predefine a set of security zones to facilitate initial configuration...