Floppy disks are pretty out of date now; not many computers can read a floppy disk anymore. (For reference as to what a floppy disk looks like, look at the save button on Word.) A tape can be used to backup video or audio data.
This is usually something like a cassette or videotape - though DVDs and CDs are taking this spot now. A network drive is a built-in backup system for computers on a small or large network. This can usually be accessed from at least one computer on the network, but if the network is large enough, any computer accessing that network can access the network drive as well.