Step 1: Recall what a MAC address identifies. Every network interface card is given a globally unique hardware identifier called its MAC address, used for delivering frames to the correct device on a local network. Step 2: Break the address down into its parts. A MAC address is written as six groups of two hexadecimal digits, the first three bytes identify the manufacturer, known as the OUI, and the last three bytes identify that specific device from the manufacturer. Step 3: Convert the byte count into bits. Six bytes total, and since each byte is 8 bits, the full address length is $6 \times 8 = 48$ bits. \[ \boxed{48\text{ bits}} \]