I have a fiber optic switch mounted in my rack(actually2 of them). Using MM fiber with ST-ST connectors from the switch to a fiber optic NIC in 3 different PC's .The switch is like a media convertor. I can extend my network up to 2km if I wanted to.You can't do that with ethernet. My whole home network was ethernet at one time. I decide to start running fiber to all of my computers about 7 or 8 months ago, I still have a few dark fibers in the attic to drop in the walls for the othe 2 PC's that are still on ethernet.