Fiber Optic
Definition
A hair-thin glass strand that guides light over kilometers using total internal reflection — the backbone of the internet.
Technical definition
A dielectric waveguide with a high-index core and lower-index cladding. Light entering within the acceptance cone undergoes total internal reflection at the core-cladding boundary, propagating with minimal loss (~0.2 dB/km for modern silica fiber).
Example
A single fiber pair can carry terabits per second — your video call likely traveled most of its journey as light pulses in glass thinner than a hair.
Common confusion
Light does not ‘bounce like a pinball’ randomly — it follows controlled total internal reflection at grazing angles. Bend the fiber too sharply and light escapes (bend loss), which is why fiber installations avoid tight corners.