MAC address identifies the network capable equipment. A media access control address (MAC address) of a computer is a unique identifier assigned to network interfaces for communications at the data link layer of a network segment.
MAC is often found printed on a sticker attached to the device. You just look for the sticker and you will know the MAC address. You can also check the the setting as most devices has option to view MAC on its user interface.
On the admin side, if you like to find out the MAC address of a device connected on your network and the info available to you is the IP address, get your command prompt running and enter the following command:
GETMAC /s xxx.xxx.xxx.xxx /v
This will instantly return the MAC address of the device using the IP address xxx.xxx.xxx.xxx.