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The basic idea of tethering is connection. Tethering an animal is connecting the animal to something else. In electronics, tethering can involve physical connection with wires. Not long ago, before the overwhelming availability of wireless networking, it was an apt physical metaphor. Now, the wireless connection is still called tethering. Even though the connection is wireless, the term still seems apt. I feel tied to my wireless modem, aware of how far I can wander before losing my connection.