As you learned in Chapter 1, strictly speaking, the word Linux refers to just the kernel, which is the fundamental, invisible program that runs your PC and lets everything happen. On its own, the kernel is completely useless. It needs programs to let users interact with the PC and do cool stuff, and it needs a lot of system files (also referred to as libraries) to provide vital functions.
The GNU Project provides many of these low-level pieces of code and programs. This is why many people refer to the Linux operating system as GNU/Linux, giving credit to the fact that, without the GNU components, Linux wouldn't have got off the starting blocks.
The GNU Project provides various shell programs, too. Some of these offer graphical functionality, but most are text only. These text shell programs are also known as terminal programs, and they're often colloquially referred to as command-line prompts, in reference to the most important component they provide. This kind of shell lets you take control of your system in a quick and efficient way. Like a GUI, it's another way of interfacing with your computer, except that you type commands, rather than use a mouse.
By learning the shell, you'll become the true master of your own system. In this part of the book, you'll learn all you need to know about using the shell. This chapter introduces the BASH shell, which is the default one in SUSE Linux.