The Bluetooth wireless standard has been an unparalleled success. It has found its way into virtually all smartphones, PCs, cars, entertainment hardware and wearables. Bluetooth SIG reports that more than 8 billion devices are currently in use. Bluetooth supports Internet of Things (IoT) technologies, making it a sure bet for the future as well. This white paper summarizes the various Bluetooth technologies with a focus on the physical layer in line with core specification version 5.0.