What is a Mac address? How Mac address is used? |Difference between IP and Mac address
When data packets from the internet hit a 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.
Your router tracks outbound data requests so that when the data for the request 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.
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.