Beneath the fancy operating system on your computer, there is another operating system. It doesn’t have all the glitter of Mac OS X or Windows 8 (or even Windows XP). For that matter, it doesn’t even have windows.
This operating system is the command line interface. By typing in text commands at the blinking command prompt, you can access the raw power of your machine, accomplishing complex tasks in a few lines of typing that would take a great deal longer in a GUI.