Fiber optic systems provide high-bandwidth communication for data networks. Single-mode fiber allows long distances with low attenuation. Multimode fiber is used for shorter distances in buildings. Cable routing from entry point to equipment rooms follows logical paths. Cable trays or conduit protect cables from damage. Proper bend radius prevents kinking and attenuation. Termination at endpoints requires specialized connectors. Single-mode connectors include LC, SC, or ST types. Multimode connectors are similar but optimized for larger core. Polishing and alignment of connectors is critical. Improper termination reduces performance and causes failures. Testing verifies cable continuity and attenuation within limits. OTDR (optical time-domain reflectometer) testing identifies breaks or poor splices. Redundancy with multiple fiber paths improves reliability. Future expansion capacity allows additional fibers without replacement.