This is a cable made up of super-thin filaments of glass or other transparent materials that can carry beams of light. Because a fiber-optic cable is light-based, data can be sent through it at the speed of light. Using a laser transmitter that encodes frequency signals into pulses of light, ones and zeros are sent through the cable. The receiving end of the transmission translates the light signals back into data which can be read by a computer.
Because fiber-optics are based entirely on beams of light, they are less susceptible to noise and interference than than other data-transfer mediums such as copper wires or telephone lines. However, the cables are fragile and are usually placed underground, which makes them difficult and expensive to install. Some fiber-optic cables are installed above ground, but if they break, they often need to be completely replaced, which is not cheap. While copper wires can be spliced and mended as many times as needed, it is much harder to fix glass fiber-optic cables.