Bluetooth, the tech that lets your phone connect with earbuds and smartwatches, is named after a 10th-century Danish ruler. King Harald “Bluetooth” Gormsson united warring clans and helped spread Christianity across Denmark. 

In 1996, Intel engineer Jim Kardach suggested the name while working on a new wireless standard because Harald was famous for bringing people together. The name stayed, and the logo is made from the king’s runic initials.