A single-mode SFP is a small form-factor pluggable (SFP) optical transceiver for single-mode fiber (SMF), which converts electrical signals into optical signals using a single mode of light. SMF SFPs are used for fiber-optic networking. A multi-mode SFP is also an SFP transceiver, but it is designed for multi-mode fiber (MMF), which uses multiple modes of light. SMF is ideal for longer distances, whereas MMF components can be lower cost and are ideal for shorter distances.