The king who united
In the 10th century Harald Bluetooth united the Danish tribes. The technology was meant to unite different devices. The logo is made of the Nordic runes for his initials, H and B.
Low Energy
Bluetooth Low Energy (BLE) uses a fraction of the power. Sensors and watches can run on it for months. BLE is also used by key finders and many smart home devices.
Sound
The sound quality in headphones is determined by the codec (SBC, AAC, aptX, LDAC, LC3). The newer LE Audio standard with its Auracast feature can broadcast sound to an unlimited number of headphones at once, for example at an airport or in a cinema.