First of all, an overview of what is fiber. Optical fiber is essentially a waveguide for light that consists of a fine strand of glass called the core surrounded by a tube of glass with different properties called the cladding. The index of refraction of the cladding is less than that of the core, causing rays of light leaving the core to be refracted back into the core. The source of light can be a light-emitting diode (LED) or some sort of laser. The buffer, strength member and jacket are meant to protect the fiber. Just a quick fact about fiber is that the measurements are in microns and the average human hair is 89 times larger than a micron. When it comes to determining the best type of fiber, again the choice comes to what are the distances required. If the customer is running a short distance and requires fiber due to the environment possibly being very noisy, POF (plastic optical fiber) may be the best choice. POF is very flexible, but has distance ratings similar to but sometimes less than that of copper. When the customer is needing more of a medium range, less than 300 meters, a multi-mode fiber (OM) may be the best choice. When referring to a multi-mode cable type the numbers refer to the different core sizes. Where the higher the OM (number) the better the grade of fiber and the further distance it can go. OM3 and OM4 fiber types are for extended bandwidth. For industrial types of applications, OM1 or OM2 should meet 90% or more of the needs. For the longest range of requirements, thousands of meters, single-mode fiber (OS) would be the best choice. OS1 has a typical maximum range of 2km and it is generally suited for indoor use only. OS2, which has a longer wavelength than OS1, has a typical maximum reach of 10km and is suited for indoor and outdoor use. Single-mode fiber is typically used in applications where long distance runs are required. The cost of the electronics required to deploy single-mode fiber is considerably higher than multi-mode fiber.