LANs (local area networks) use fiber optics primarily in the backbone but increasingly to the desk. The LAN backbone often needs longer distance than copper cable (Cat 5/5e/6) can provide and of course, the fiber offers higher bandwidth for future expansion. While fiber is still primarily limited to LAN backbones. A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. A basic fiber optic system consists of a transmitting device, which generates the light signal; an optical fiber cable, which carr es the light; and a receiver, which accepts the light signal transmitted.