Copper
Copper cables are literally made from copper material, transferring data through electrical pulses. Intended initially to transmit voice data, copper cables have been repurposed to transfer internet data and are what most cable providers use today.
Because of the older material, copper wires can only send data for limited distances at limited speeds. Copper wires have been around for a long time, making copper a suitable and reliable connection option for more rural areas of the country.