Where copper cabling uses electricity to transmit signals from one end to another, fiber optics use light pulses to accomplish the same purpose. The fiber optic cable is made of a transparent glass core surrounded by a mirror like covering called cladding. Light passes through the fiber optic cable, bouncing off the cladding until it reaches the other end of the fiber channel – this is called total internal reflection. In today’s high speed networks, Graded Index Multimode fiber or Step Index Single mode fiber cable is used to improve light transmission over long distances. Multimode fiber optic cable has a larger core and is typically used in short runs within buildings. Single mode fiber optic cable has a smaller core and is used in long distance runs typically outside between buildings.