Bluetooth was named after a 10th-century Viking king who united Denmark and Norway — the logo is his initials in Nordic runes, and Ericsson’s engineers picked it in 1997 as a placeholder that stuck

It is the bind rune of Harald Gormsson, a Danish king who ruled from around 958 to 986 AD and is better remembered by his nickname: Harald Blåtand, or Harald Bluetooth. In 1996, the companies agreed to merge their work into a single royalty-free standard, but the consortium needed a name. Kardach was reading Frans G. Bengtsson’s historical novel The Long Ships, about Viking raids in the reign of Harald Bluetooth, and — as he later recounted in EE Times — the parallel struck him. The consortium was trying to unite fractious PC, phone and accessory makers into a single wireless standard. Bluetooth, Kardach argued, was the obvious placeholder until marketing came up with something better.