The Media Access Control card interfaces your computer to the network and has a unique number. Learn how to get that number, here.

Your computer's interface number for your ethernet connection is different than that for your wireless connection. It serves as a serial number, unique in the whole wide world.

This is not to be confused with your IP number.

For Macs

The network adapter information (such as the MAC addresses for your device) is found in the system preferences, network, advanced section.

For Windows

You can view much of the information by opening a command prompt and running IPConfig as shown below.

Start => Run. Then type in:

CMD

Type in:

ipconfig /all

This provides information, such as:

“Host name” is the machine name
“Physical address” = NetCardAddress (there will be more than one on Laptops with WiFi). This is the MAC address- distinguish between wired and wireless!
IP Address