Why is Bluetooth named after a 10th-century Viking king?

Because an Intel engineer liked the symbolism, and the placeholder never got replaced. In 1997, Jim Kardach of Intel, one of the founders of the Bluetooth Special Interest Group, proposed the name for a short-range wireless project. A conversation with Sven Mattisson, who told tales of Scandinavian history from Frans G. Bengtsson's Viking novel The Long Ships, had introduced him to Harald Bluetooth, the 10th-century Danish king who united the disparate Danish tribes into a single kingdom. Kardach liked the parallel: Bluetooth would similarly unite communication protocols.

According to Bluetooth's own official account, the name was only ever meant to be temporary, a placeholder until marketing came up with something sleeker. The leading replacement candidates were 'RadioWire' and 'PAN', short for Personal Area Networking. PAN looked like the frontrunner until a search revealed it already had tens of thousands of hits across the internet, and the trademark search for RadioWire couldn't be finished before launch. Bluetooth was the only name left standing, and it spread through the industry so quickly that it became permanent before anyone could swap it out.

The technology itself began years earlier, in 1989, when Nils Rydbeck at Ericsson Mobile in Sweden set out to build wireless headsets. By 1994, his team was working seriously on the project, and by 1997 they had something that worked. Because neither Ericsson phones nor IBM's ThinkPad notebooks dominated their markets at the time, IBM's Adalio Sanchez and Ericsson's Rydbeck agreed to make it an open industry standard; IBM recruited Intel, which brought in Toshiba and Nokia. The Bluetooth Special Interest Group launched in May 1998 with those five founding companies, and the first Bluetooth device, a hands-free headset, debuted in 1999 to an industry award. Even the logo nods to its Viking namesake: it merges two ancient runes that happen to be Harald Bluetooth's own initials.