In EIA/TIA-598, the outer jacket color of different optical fibers for non military applications is defined. Single mode fibers use yellow outer jacket, while multimode optical fibers use orange, aqua, violet, lime green to help quickly identify different types of multimode. The outer jacket color quickly identifies the type of fiber inside. This color-coding system is standardized under TIA-598-C, making it easier for technicians and installers to identify. There are six fundamental colors in the visible spectrum – These are red, orange, yellow, green, blue, and violet. When we see a rainbow, we are seeing these principal spectral colors and from these colors come all other colors that we see with our eyes.