Fibre optic cables are long, thin strands of drawn glass (approximately the diameter of a human hair) that carry light signals in modes. This is the path that the light beam follows when travelling down the fibre. The simplest structure, single mode fibre contains a very thin core, which all signals travel down. It is typically used for CC ITV, internet and telephone applications where the signals are carried over long distances and at high speeds by single mode fibres wrapped into a bundle.
Multimode fibre is much larger (roughly 10 times larger than a single mode cable) and carries the light signal on a variety of different, or multiple, paths/nodes. This type of cable can only send data over short distances so is more suitable for interconnecting computer networks. There are four types of multimode fibre optic cables; OM1, OM2, OM3 and OM4 which all have a minimum Modal Bandwidth requirement.