We have all been asked the glass half-empty/half-full question. Dark fiber offers those seeking fiber-optic telecommunications solutions a glass that is half full already. The term “dark fiber” was coined when the potential network capacity of telecommunication infrastructure was discussed but now also refers to the increasingly common practice of leasing fiber optic cables from a network service provider. Dark fiber or unlit fiber (sometimes known as fibre) is the name given to fiber optic cables which have been laid in the ground but have yet to be used. That’s right, the cable is already there your glass has been half filled already, or your completely empty glass is now only half-empty. The cables are not already connected to any device on either end. That half of the glass is yours to fill. They were installed with the purpose of being used at some point in the future. How you mix the rest of the glass depends on your needs and tastes.