MAC address (Media Access Control address) is a 12 character identifier for your network adapter. In theory, it is unique for each network adapter. The first half of the MAC address (OUI) gives information about the manufacturer.
How to get your MAC address
Note that: For routers/modems provided ISPs, the MAC address is normally written below.
Go to the Start Menu and select the Run option
Enter cmd to open the command prompt window.
Copy and paste the command ipconfig. For XP users, use the command getmac instead.
You will find the MAC address in the section labelled as Physical Address. It is series of 6 groups of numbers and letters.
Open a terminal and type the following command: ifconfig
The MAC address is written next to HWaddr
Mac OS X
Apple menu > About this Mac > More info > Network.