There are five main types of multimode fiber, standardized by ISO/IEC 11801: OM1, OM2, OM3, OM4 and OM5. Multimode fiber (MMF) is a kind of optical fiber mostly used in communication over short distances, for example, inside a building or for the campus. 5 microns that enables multiple light modes to be propagated. In this white paper, we will review the basics of multimode fiber and the evolution of the different fiber standards.