Several Ethernet cables connected to switch ports

If you’ve ever tried to identify devices on a network or search for a nearby Bluetooth device, chances are you’ve dealt with MAC addresses. But what are they exactly, and how are they different from IP addresses?

What Is a MAC Address?

Multiple hardware and software elements work together every day to connect us to the internet and get data to our devices. Hardware devices like routers and cables transmit the data we need, while software like border gateway protocol (BGP) and internet protocol (IP) addresses direct those data packets to and from those devices. Without both working together, we couldn’t get online.

One of those critical elements is the media access control (MAC) address. MAC addresses are associated with specific devices and assigned to them by the manufacturer.

Other names used for MAC addresses include:

  • Networking hardware address
  • Burned-in address (BIA)
  • Physical address
  • Ethernet hardware address (EHA)

Wi-Fi, Bluetooth, and Ethernet connections all use MAC addresses.

MAC addresses work with the card in your device that lets it connect wirelessly to the internet, called a Network Interface Controller (NIC). MAC addresses are used to identify which device is which on your local network so that data gets sent to your computer and not your roommate’s smartphone.

MAC addresses are always a 12 digit hexadecimal number, with the numbers separated every two digits by a colon or hyphen. So a MAC address of 2c549188c9e3, for example, would be displayed 2C:54:91:88:C9:E3 or 2c-54-91-88-c9-e3.

Large network adapter manufacturers like Dell and Cisco will often code their identifiers, called their Organizationally Unique Identifier (OUI), into the MAC addresses of devices they make. They’re always the first six digits. Dell’s, for example, is 00-14-22.

RELATED: What Is a Network Adapter?

How Does a MAC Address Work?

When data packets from the internet hit your router, that router needs to be able to send them to the right device on its network. It does this using MAC addresses, assigning a private IP address to each network-connected device based on that device’s MAC address. This is different from the IP address your internet service provider (ISP) assigns you—that’s your public IP address.

Your router tracks outbound data requests so that when the data comes back, it can attach the correct private IP to the data packets, then send them along to whichever device’s MAC address matches that private IP.

Devices can have more than one MAC address because they get one for every place they can connect to the internet. If your laptop has an ethernet port and Wi-Fi, for example, it would have different MAC addresses for the Wi-Fi connection and the Ethernet connection. Bluetooth also uses its own MAC address.

RELATED: Wi-Fi vs. Ethernet: How Much Better Is a Wired Connection?

How Are MAC Addresses Used?

In addition to sending your data to the right place, your wireless router also uses MAC addresses to secure your connection by only accepting traffic from devices with MAC addresses that it recognizes. This is called MAC filtering.

MAC addresses can also be used by technicians to troubleshoot connection problems on a network. Because they’re unique to each hardware device, it’s easier to pinpoint which piece of hardware connected to the network is sending and receiving data by looking at the MAC address. From there, they can see which device is having trouble connecting.

How Do I Find My MAC Address?

If you need to find the MAC address for your device, you can usually do it by going into the settings menu. You can follow our guide to finding the MAC addresses on your Windows device, whether by the Settings app or by the command prompt.

It’s also easy to find the MAC address on a Mac computer. In System Preferences, click the Network icon, select the interface you want to use, then click Advanced. You’ll see the MAC address listed under the Hardware tab.

Many more devices, including smart TVs, game consoles, and smartphones have their own MAC addresses that you can find.

If you want to, it’s also possible to change or “spoof” your MAC address.

RELATED: How to Permanently Change Your MAC Address on Linux

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John is a freelance writer and photographer based in Houston, Texas. His ten-year background spans topics from tech to culture and includes work for the Seattle Times, the Houston Press, Medium's OneZero, WebMD, and MailChimp. Before moving to The Bayou City, John earned a B.A. in Journalism from CSU Long Beach.
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