The Bluetooth logo is a combination of two Viking runes.
Why it is true
The symbol is actually the superposition of the initials of King Harald Bluetooth, written in the ancient Nordic runic alphabet, uniting devices just as he united tribes.
Source: Wireless History
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.