About

The mac address is a local net identifier for a network interface (adapter).

Mac Header

It's part of every packet in the mac header

How to get it on Windows?

With netsh:

netsh wlan sh int

Name                   : Wi-Fi
Description            : Intel(R) Dual Band Wireless-AC 8265 #4
GUID                   : xxxxxxxxxxxxxxx
Physical address       : 5c:5f:67:6b:cb:9b   <---- The mac address
Interface type         : Primary
State                  : connected
SSID                   : xxx-xxx
.....................