In optical modules, “core” refers to the light-transmitting channel in the fiber. A 1-core module uses a single fiber core for data transmission, while a 2-core module uses two cores. They are easier to set up and give steady communication. They use a thin fiber. SFP (Small Form-factor Pluggable) is a compact, hot-pluggable network interface module used to connect network devices (switches, routers, firewalls) to fiber optic or copper cables. Think of it as the “translator” for your network equipment, converting electrical signals into optical signals. A fiber optic transceiver (also called an optical transceiver) is a compact module that both transmits and receives data signals through optical fibers.