Optical fibre is only marginally thicker than a human hair and is made by drawing out glass or plastic to the required thickness.
Optical fibres (or optical fibers) are most commonly used to send light from one end of the fibre to the other. They are also used widely in fibre-optics communication. When used in fibre-optics communication the fibres are able to transit over higher bandwidths and longer distances than traditional wire cables. There is also less loss with fibre-optics than with wire. Another plus with fibre is that they are not suject to electromagnetic interference, a problem that plagues metal wire.
Joining optical fibres so that there is minimal loss is more complicated than joining electrical wire and it requires careful cleaving, precisely aligning the fibre cores and coupling of aligned cores.
Fibre optics is the field of engineering and applied science which is concerned with the application and design of optical fibres.