A serial port is not a peripheral, but it is a serial communication interface through which information transfers in or out one bit at a time. These interfaces are one of the most important communication ports we can have in an embedded device. In fact, in the first chapter, we discovered that we can get full control of our BeagleBone Black only by getting access to its serial console (which normally runs over a serial port even if, in our case, it has been emulated via a USB device).

In the industry market, we can find tons of peripherals that use a serial port to communicate with the CPU, so that's why we must know a bit more about how this communication interface works, and how we can get access to its connected devices in order to exchange data with them.

A peripheral using a serial port to communicate with the CPU is normally called a serial peripheral or serial device.