What is a MAC address?
The Mac address is a kind of serial number of the hardware that comes in addition to the IP address, assigned by the service provider or the administrator of a network. Unlike the IP address, the MAC address is supposed to never change: when the computer is moved (physically), a new IP address is assigned to it, however its MAC address remains unchanged. Each MAC address is unique in the world: it can be considered as a kind of license plate for electronic devices. When you offer your visitors / customers public Wi-Fi access via hotspots, you are under a legal obligation not to keep the names of the people who connect, but to archive the MAC addresses of the devices used. This archiving should last 1 year.