Fiber means a thread or filament from which a vegetable tissue, mineral substance, or textile is formed; but here these threads are formed by very thin glass so that the light can travel in it. These glass threads are so thin that they can be wrapped together to form multi-channel cables.
Optical fiber is a type of cable that is made up of thin strands of glass or plastic that are used to transmit information over long distances using light. The fiber optic cable consists of a core, which is where the light travels through, and a cladding, which is a layer of material that surrounds the core and helps to keep the light in the core. The cable may also have a protective outer layer called a jacket.