Coaxial cables have limitations such as broadband transmission medium which can be overcome by the use of optical fibres. Optical fibres carry light waves (representing electrical impales) by the principle of internal reflection. These fibres carry signals in the form of light, and hence can carry large volumes of data at high speed, and are resistant to interference. Thus, they are 'clearer' lines with less noise. Though they were expensive when first introduced, but nowadays costs hive fallen to such a level that they are being used by some organisations for their local area networks.