Fibre-optic cable is another transmission media that uses light to transmit signals rather than the electric current. At the centre of this is a glass core through which light propagates. This core is surrounded by a glass cladding with a lower index of refraction than the core, to keep all the light in the core. It is followed by thin plastic jacket to protect the cladding. These fibres are together grouped in bundles protected by other covering. When one end is exposed to light, the light travels all the way to the other end – bending around corners along the way. As light travels at a very fast speed so they can easily carry data at light speed. The speed of fibre optic cable is about 100 Gbps.