The shielding protects it form electrical interference. Standards are specified under 10 base 2 or 10 base 5 Cable has a large bandwidth of up to 600 MHz and data up to 100 mbps, is less susceptible to interference and noise. Thus the medium can accommodate more than 50 video channels, offers cleaner video signals, and so is most widely used in the cable television industry. It is not as expensive as fiber and is also used in LANs and for Internet Access. But cable is bulky making it difficult to install and is not a very secure medium since it can be tapped into easily.
Optic fiber is a relatively new and rapidly advancing technology.
The fiber has a thin core strand of high purity glass, a surrounding cover of another kind of glass called cladding and another plastic protective cover on top and the whole not more than hair thick. The technology uses the differing reflective properties of the core glass and the cladding. The light signals can be modulated for data transmission. There are two primary types of fiber single mode and multimode. Multimode fiber has a core thickness of more than 50 microns where reflection off the cladding is greater and leads to dispersion and so can be used over shorter distances.