This document discusses optical fiber connectors. It begins by introducing the ferrule, which is a cylindrical tube used in connectors to precisely align the fiber cores. The document then covers the major types of connectors that have been introduced, including ST, SC, LC, FC, MU, and MPO connectors. ST and SC connectors became dominant in the 1980s-1990s due to their low loss and ease of use. Newer connectors like LC and MPO provide higher density by reducing size and combining multiple fibers. Proper connectors are important for achieving low insertion loss while providing easy installation and connection/disconnection of fibers.