The coaxial cabling used in standard Ethernet or 10Base5 networking. Thicknet coaxial cabling is usually 3/8 inch in diameter. It is fairly rigid, has an impedance of 50 ohms, and can carry signals up to 500 meters (1640 feet) - hence the designation 10Base5 for «10-Mbps baseband transmission over 500 meters».
To connect a computer to a thicknet cable, you attach a vampire tap to the cable. The tap pierces the cable’s insulation layers and makes contact with the signal-carrying copper core. The tap is connected to a transceiver, and a drop cable connects the transceiver to an AUI connector on the computer’s network interface card (NIC).