SFP is an abbreviation for SMALL FORM PLUGGABLE (small pluggable) and can be simply understood as an upgraded version of GBIC.
SFP Module The volume is halved from the GBIC module, with only the thumb size. You can configure more than one more port number on the same panel. The other functions of the SFP module are basically the same as GBIC.
Some switch manufacturers say the SFP module is miniaturized GBIC (MINI-GBIC)  The composition of the SFP optical module is: Laser (including transmitter TOSA and receiver ROSA) and circuit board IC and external accessories composition, external accessories have shell, base, PCBA, pull ring, buckle, unlock parts, rubber plug composition, in order to identify convenient generally with the color of the pull ring to identify the parameter type of the module.