In reply to Santo.

Santo,
The Small Form-factor Pluggable (SFP) optical transceiver modules allow use of fiber optics cabling to connect the switch to the network. SFP(1G) , SFP+ (10G) are both supported on the Catalyst 3850. The Catalyst 9300 supports SFP, SFP+ and a new SFP28 25G uplink as well as QSFP, 40G uplink modules. The Catalyst 9500, in addition to those mentioned, also supports QSFP28 modules for 100G optical links.
Jeff