SC/ST connectors are used for connecting fiber-optic cabling to networking devices. SC stands for subscriber connector and ST stands for straight tip. See the full article to find more.
What is SC and ST connectors?
Connector types that are generally used for connecting fiber-optic cabling to networking devices. Both are recognized by the Electronic Industries Alliance/Telecommunications Industry Association (EIA/TIA) 568A standard.
SC stands for subscriber connector and is a standard-duplex fiber-optic connector with a square molded plastic body and push-pull locking features. SC connectors are typically used in data communication, CATV, and telephony environments.
ST stands for straight tip, a high-performance fiber-optic connector with round ceramic ferrules and bayonet locking features. ST connectors are more common than SC connectors.
You can generally use SC and ST connectors with either single-mode or multimode fiber-optic cabling. Coupling receptacles for these connectors come in either panel-mount or free-handing designs. For narrow space installations, you can get 90-degree boot versions instead of straight versions. SC and ST connectors come in both simplex and duplex form.
See examples (on Amazon): ST to ST Fiber Patch Cable Multimode Duplex (3.28ft/1m), or Tripp Lite Duplex Multimode 62.5/125 Fiber Patch Cable (SC/SC), 5M (16-ft.).

SMA connector
A third type of fiber-optic connector is the SMA connector, which has a threaded-nut locking feature. Subtypes include SMA905 and SMA906 connectors.
Military-grade connectors
The best fiber-optic connectors are military-grade connectors. These connectors satisfy the MIL-C-83522 (ST) specifications and are corrosion-proof; have isolated relief boots to reduce cable strain; and are heat, shock, vibration, fungus, and salt-spray resistant.