What is MAC address?

 In a computer network MAC (Media Access Control) address defines the network interface hardware of a network device or a computer. Each computer has a unique MAC address for its modem, ethernet card or wireless network card and each and every one these addresses are different from each other. MAC addresses are in the format of XX:XX:XX:XX:XX:XX and since this is a hexadecimal expression, it can contain numbers from 0 to 9 and letters A-F as well. For example a MAC address can be like this: 00:11:85:dc:4a:b8.

Below you can see how to find MAC addresses of devices according to the operating systems:

Windows Operating Systems:

After you introduce your network interface to the operating system, you can click "Start" --> "Run"  and write "cmd" inside the opening box and press "enter". In the DOS window that opens execute the command "ipconfig /all"and press enter. 

The information that comes to your window after you execute the command contains all the information about your network interfaces and their configuration.  The "Physical Address" of the "Local Area Connection" gives your ethernet interface's MAC address and the "Physical Address" of the "Wireless Network Connection" gives your wireless network adapter's MAC address.

MAC OSX Operating System

UNIX based Operating Systems (Linux, Free/Open/NetBSD, Solaris/SunOS)

 In Unix based operating systems, the network interfaces are labeled as bge0, ie0, eth0 and the like. To reach the information about your network  interfaces you should give the command "su" at command line iterface to become "root" of the system. Then write down "ifconfig -a" and press "enter". You can get the information about your network adapter in the following ways.

Example 1: (LINUX)

# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 00:60:08:C4:99:AA
          inet addr:172.16.40.2  Bcast:172.16.40.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:15647904 errors:0 dropped:0 overruns:0
          TX packets:69559 errors:0 dropped:0 overruns:0
          Interrupt:10 Base address:0x300

Your ethernet MAC address is "00:60:08:C4:99:AA" following HWaddr expression.

Example-2 (Other UNIX based systems)

# ifconfig -a
le0: flags=863 mtu 1500
        inet 172.16.40.2 netmask fffff800 broadcast 172.16.40.255
        ether 00:60:08:c4:99:aa 

Your MAC address is  "00:60:08:C4:99:AA" following the expression "ether"

NOTE-1 :Solaris/SunOS systems doesn't show the first 0 in the first duo. (Example 3 - 4)

Example-3

# ifconfig -a
le0: flags=863 mtu 1500
        inet 172.16.40.2 netmask fffff800 broadcast 172.16.40.255
        ether 0:60:08:c4:99:aa

MAC address : "00:60:08:C4:99:AA"

Example-4

# ifconfig -a
le0: flags=863 mtu 1500
        inet 172.16.40.2 netmask fffff800 broadcast 172.16.40.255
        ether 8:0:06:c4:99:aa

MAC address : "08:00:06:C4:99:AA"