What can I do with my MAC address

Now that you have some background, what do you do with a MAC address?

• You let your computer use it automatically – without worrying about it – in much the same way you would let your car pick gears using an automatic transmission.
• You configure your router with it, if you want to use MAC address filtering to block access by unknown computers and devices.

Note that bad guys can "spoof" MAC addresses, so MAC address filtering alone is like the "easily broken down" screen door of security. If your WiFi router has WPA2 security or better, and you choose a WiFi password which isn't easily guessed, that will do a lot more to keep undesirables out of your network than MAC address filtering would.

Note that MAC (Media Access Control) is not a reference to Apple Macintosh computers. It's an acronym from the computer networking world. Macs have MAC addresses because they have network interfaces – and not because they are Macs. PCs running Windows or Linux also have MAC addresses, for the same reason.

For real confusion, consider the acronym ATM, which has at least three meanings:

• Automated Teller Machine
• Adobe Type Manager (old font-handling software)
• Asynchronous Transfer Mode (a high-end networking technology that fell out of favor)

Theoretically, you could have an ATM that used ATM to help display text, and ATM to talk to the bank …

What are you attempting to do? Also, it may help you by re-writing your question with more information. Please refer to Writing an effective Apple Support Communities Question to get an idea of what we need from you in order to help you out.

Oversimplifying things a bit, a MAC (Media Access Control) address helps to uniquely identify a network interface. A network interface would be something like an Ethernet port or a WiFi adapter – though this is just scratching the surface.

There are 48 bits in a MAC address, and half of the range is set aside for globally-unique MAC addresses - which means there are enough globally-unique addresses to identify approximately 140.7 trillion interfaces.

There is structure to MAC addresses, but all it tells you is which organization issued them – not where a particular interface is located in the world. So when you connect to the Internet, there's another, higher level of addressing: Internet Protocol (IP) addresses. Those are structured in a way that does give clues as to where to route packets.

Most of the time, a particular MAC address is only involved in local hops. E.g., your router sees your computer's MAC address, and needs to know it to get replies from the Internet back to your computer. The computers and routers out on the Internet don't know (or want to know) your MAC address. The MAC addresses that they care about are the ones that let them take care of THEIR local hops. It's IP addresses that "survive" the long haul.

There may be exceptions to this, such as when a software vendor records your MAC address as a part of a DRM "activation" scheme … basically using it as a serial number with which to identify your machine (or technically, to identify an interface).

Are you asking about your MAC ...Media Access Control: https://slts.osu.edu/articles/whats-a-mac-address-and-how-do-i-find-it/ or some sort of iMac identifier?