MAC address is media access control address. It is a computers unique address. It is a unique value associated with computers network adapter. It is a 12-digit hexadecimal numbers. The first half contains ID number of the adapter manufacturer and the second half contains serial number assigned to the adapter by the manufacturer. It is a hardware address that uniquely identifies each node of a network. When you're connected to the Internet from your computer IP address and computer's physical (MAC) address are recorded.
MAC address are generally fixed but IP address may change when the network device changes from one network to another.
Find MAC address of your computer.
Click Start and go to All Programs.
Click accessories and open Command Prompt.
Type ipconfig /all and press enter.