Bluetooth is a wireless communication standard for exchanging data and audio between nearby electronic devices. Its specifications and trademark are managed by the Bluetooth Special Interest Group.
Bluetooth is named after Harald "Bluetooth" Gormsson, the 10th-century Viking king who united Denmark and Norway—as the tech would unite PCs and phones. Its logo merges his initials in runes ᚼ and ᛒ. A placeholder name, it stuck. The nickname likely came from a dead, bluish tooth.