Getting started with the HC-06 Bluetooth module
Adding wireless communication to an Arduino project usually starts with a Bluetooth serial module, and the HC-06 is one of the most common choices. It's cheap, widely available, and does one job well: it lets a phone or computer connect to your board and exchange data as if the two were joined by a cable. Four pins, one operating mode, and a small set of configuration commands is the whole picture. That simplicity comes with a real constraint though, and knowing it upfront saves time later, since the HC-06 only accepts incoming connections and can't reach out to another device on its own.
