In a scramble to track, and thereby stem the flow of, new cases of the Coronavirus, Governments around the world are rushing to track the locations of their populace. One way to do this is to write a smartphone app which uses Bluetooth technology, and encourage (or mandate) that individuals download and use the app. The aim of this piece is to provide more detail on the technology itself, rather than a deep dive into the risks and whether or not Bluetooth technology should be used.