They allow you to see data sent to and from your microcontroller, and that data can be used for a number of reasons including troubleshooting/debugging, communication testing, calibrating sensors, configuring modules, and data monitoring. In short, serial terminal programs make working with microcontrollers that much simpler. This tutorial is here to help you understand what these terms mean and how they form the larger picture that is serial communication over a terminal.
For someone who isn't familiar with these terms and the context in which they are used, they can be confusing at times. These are all words that get thrown around a lot when working with electronics, especially microcontrollers.
