Fiber optic cables are mainly categorized into two types based on application scenarios and structure: Single-mode Fiber (SMF): Features an extremely thin core (about 9 microns), allowing only one light mode to propagate. Suitable for long-distance, high-speed transmission (e.g., backbone networks, inter-city communication). Multi-mode Fiber (MMF): Has a thicker core (e.g., 50 microns, 62.5 microns), supporting multiple light modes. Designed for short-distance transmission (within several hundred meters), commonly used in local area networks (LANs) and data centers.