The Media Access Control address or MAC address is unique address similar to an IP address that is associated with a particular piece of hardware. The MAC address helps users identify the type of hardware and the manufacturer of the device. MAC addresses help to differentiate between multiple devices on a network. Without a MAC address your network would not be able to determine between your computer, tablet and IoT device. This would make sending and receiving network traffic impossible.
MAC addresses are identified by a 12 digit hexadecimal number with two character sections separated by colons. Here is an example of a MAC address (2B:54:91:81:C9:E3). When your router receives a packet from another device over the internet it then needs to direct that packet to the right device on the network. This is accomplished by the router identifying the correct device by its MAC address. This information is stored in a database called the routing table.