I appear to have 3 IP addresses. Why?

The 10.0.1.13 is your address on your local network, while the 24.130.184.130 is your address as part of the external network. Your router mediates between the two systems. At least that's my understanding, and if it's wrong, we'll both hear from an expert soon! 🙂

Hmmm, just saw the third - not sure why it's also listed as a 192.*.*.* - how was that display generated? If I remember correctly, you can set up your local network to use 10.*.*.* or 192.*.*.* (in Airport Utility?).

1. The Mac can have as many internal IP addresses as network interfaces are active. So if you have the Wi-Fi up and connect via a patchcord, you will have 2 IP addresses as shown on the Network perfpane. Only one will be used at a time, depending on the service order of the interfaces (one on top gets privileged).

2. The IP address given to each interface, usually via DHCP, depends on the network policies set by your network administrator and/or the device it is plugging into. If in the 10.x.y.z, the 172.16.y.z-172.31.y.z or the 192.168.y.z ranges, then it is a local private IP address. Before it can go out to the rest of the world, it needs to be translated to public IP address via a NAT or PAT process on an router, access point or firewall.

3. As it traverses your ISP's multiple subnetworks, it is not uncommon for your traffic to be translated over several private networks, resulting in different intermediate IP addresses showing up.