Optical fiber refers to the transmission of information as light impulses along a glass or plastic wire. There are three main types of optical fiber: multimode, single mode, and photonics. Optical fiber has several advantages over metal cables, including greater bandwidth, lower power loss allowing for longer transmission distances, immunity to electromagnetic interference, lighter weight, and lower safety risks. However, optical fiber also has higher installation costs and requires protection and signal repeating over long distances. Optical fiber has applications in networking, high-speed data transmission, harsh environments, and various industries.