The three color line matching in optical fibers refers to the color coding system used for categorizing different types of optical fiber cables. Typically, this involves a set of three colors, often black, white, and a third color that varies depending on the cable's specifications. The color coding is used for easy identification and installation. For instance, black and white are commonly used for single-mode fibers, while the third color may indicate the fiber's core diameter or the type of cable jacket. This system is crucial in ensuring proper cable management and system performance.