Explain WAN routing please

I have a DLINK DIR-655 router. I have noticed that in the routers setup menu,under advanced that there is a section called routing.
It looks like this:


Metric Interface
Name
Destination IP

Netmask
Gateway

Name
Destination IP

Netmask
Gateway

I understand basic routing and subnetting.
I do not the concept of WAN routing.
Is this just for when your lan is subnetted and you want the shortest path to the gateway with internet access?

I could use some guidance here concerning when and why under which circumstances one would use this feature.

Thanks, I really appreciate the down to earth networking tutorials that Firewall.cx hosts.

I think it would be very difficult for anyone to comment on the requirement of those fields that you asked for just looking at the title.

Infact the technical specifications sheet of the produc would be more helpfull.

Also, someone who has actually worked with that device would be able to tell more about that.

Maybe this helps: www.firewall.cx/ftopict-5455-.html