What technology is named after a tenth-century ruler of Denmark and Norway?

The story behind the answer

Bluetooth is named after Harald “Bluetooth” Gormsson, a 10th-century king of Denmark (and parts of Norway), known for uniting warring tribes—just as Bluetooth unites different devices for short-range communication. Engineers chose the name during early collaboration on the wireless standard to symbolize interoperability across brands and platforms.

A fun detail: the Bluetooth logo merges two Viking runes—Hagall (H) and Bjarkan (B)—Harald’s initials. The nickname “Bluetooth” likely referred to a darkened tooth, a memorable hook to recall the name. Remember it this way: the king who united people lends his nickname to the tech that unites gadgets.