|  | 9.4 | LAN Switching
| 9.4.3 | The MAC address
The MAC (Media Access Control) address is a layer 2 address, which is burned into the ROM chip on an Ethernet network interface card (NIC). This is a unique 48 bit number, which is written as eight hexadecimal numbers. The first 24 bits represents the vendor or maker of the of the NIC card (Some vendors may have more than one 24 bit vendor code assigned to them.) Each vendor code is a serial number unique to that vendor. As shown in the Figure, The 24 bit vendor code together with the 24 bit vendor controlled and assigned serial number, make up a unique 48 bit MAC address.