Mentioned in The Hitchhiker's Guide to the Galaxy of Douglas Adams, Sub-Etha is the name of the vast communication network used throughout the galaxy for any kind of data transmission like hitchhiking a space-ship or browsing through the pages of the Hitchhikers' Guide to the Galaxy itself.

For a fiction novel released in late 1970s, concepts like "distributed information " and "wide area networks" were ideas ahead of its time and probably along with the intelligent humor, caused the whole series to become all time best-sellers.