A media converter is a device that transforms one data communication port into another, enabling the conversion between different types of communication ports, including fiber ports and electrical ports like RJ-45 Ethernet.
In other words,
A media converter is a device used in computer networking that facilitates the conversion of communication protocols between different cable types. It specializes in transforming signals from copper cables, specifically CATx/UTP, to fiber optic cables. Media converters are frequently deployed in pairs to integrate fiber segments into copper networks, enabling longer cabling distances and enhanced immunity to electromagnetic interference. Additionally, they possess the capability to extend local area networks (LANs), modify link speeds, and adapt to various fiber modes.