Fiber optic technology experienced a phenomenal rate of progress in the second half of the twentieth century

There are three types of fibers commonly used: 
Singlemode Fibre(SMF)
Multimode Fibre (MMF)
Plastic Optical Fiber (POF).

They are transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss.

Fiber optic cable functions as a “light guide,” guiding the light introduced at one end of the cable through to the other end. The light source can either be a light-emitting diode (LED)) or a laser.

Two basic cable designs are:

Loose-Tube Cable:

In a loose-tube cable design, color-coded plastic buffer tubes house and protect optical fibers. A gel filling compound impedes water penetration. Excess fiber length (relative to buffer tube length) insulates fibers from stresses of installation and environmental loading. Buffer tubes are stranded around a dielectric or steel central member, which serves as an anti-buckling element.

Loose-tube cables typically are used for outside-plant installation in aerial, duct and direct-buried applications.

Tight-Buffered Cable:

With tight-buffered cable designs, the buffering material is in direct contact with the fiber. This design is suited for “jumper cables” which connect outside plant cables to terminal equipment, and also for linking various devices in a premises network

Multi-fiber, tight-buffered cables often are used for intra-building, risers, general building and plenum applications.

Advantages Of Fibre Optics:

A technology that uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.

Fiber optics has superior transmission properties over traditional metal communicationslines:

Fiber optic cables have a much greater bandwidth than metal cables. This means that they can carry more data.

Fiber optic cables are less susceptible than metal cables to interference.

Fiber optic cables are much thinner and lighter than metal wires.

Data can be transmitted digitally  

Fiber optics is a particularly popular technology for local-area networks. In addition, telephone companies are steadily replacing traditional telephone lines with fiber optic cables. In the future, almost all communications will employ fiber optics.