Actually, they carry only analog signals. Data rates of several Mbps common. Spans distances of several kilometers. Data rate determined by wire thickness and length. Good, low-cost communication.
Physical connection consists of metal pin touching the copper core.
A special tool drills a hole into the cable, removing a small section of the insulation, and a special connector is screwed into the hole. The tap makes contact with the copper core. With a T junction , the cable is cut in half, and both halves connect to the T junction. A T-connector is analogous to the signal splitters used to hook up multiple TVs to the same cable wire. Data rate depends on physical properties of cable, but 10 Mbps is typical.