It's a kind of safety line to keep your packets from wandering off and getting lost on their way to the cloud. Helps reduce the "401 not found" pages you sometimes encounter.

Is this for computers like they had in the really old movies like Back to the Future?

Yep, exactly that. We used the 1.21 Gigawatts standard, which was only half as groovy as today's 2.4 Ghz WiFi.