Apple:

To communicate with a Wi-Fi network, a device must identify itself to the network using a unique network address called a media access control (MAC) address. If the device always uses the same Wi-Fi MAC address across all networks, network operators and other network observers can more easily relate that address to the device’s network activity and location over time. This allows a kind of user tracking or profiling, and it applies to all devices on all Wi-Fi networks.

So if you always use your device’s actual MAC address at, say, your local Starbucks, it becomes easy to uniquely identify that device and track you.

As Android did last year, Apple has given you the ability to randomize your MAC address. Follow the headline link to learn more but here’s how to turn this on/off:

• Go to Settings > WiFi
• Tap your WiFi network
• Look for the Private Address toggle

Private Address is likely already on. If it is and you never noticed, perfect!

Since a randomized address is seen as a new network device, this might cause you to see a “new network device” alert each time you get on your home network (if you are set up to monitor such things). Apple lets you customize a network to turn private addresses on or off to address that issue.