Okay, we've covered the kernel's major responsibilities. Now, let's discuss the final major aspect of an operating system, how humans interact with it. This is what we call, the userspace. When we interact with an operating system, we want to do certain functions like create files and folders, open applications, delete items, you get the idea. There are two ways that we can interact with our OS, with a shell or a graphical user interface. There are also some shells that use graphical user interfaces, but we'll work with the command line interface or CLIA shell for the most part. This just means that we'll use text commands. A graphical user interface or GUI, is a visual way to interact with a computer. We use our mouse to click and drag, to open folders etc. We can see everything we do with it. You probably use a GUI every day without realizing you're using one. To watch this video, you probably used a GUI. Clicking icons and navigating menus to open your web browser and navigate to the Coursera website. People usually recognize a device or product based on its GUI. You might be able to spot the difference between a computer running Microsoft Windows or Mac OS based on the design of the windows, menus and icons. You've probably seen GUIs in other places too, like mobile phones and tablets, ATM machines and airport kiosks. A shell is basically a program that interprets text commands and sends them to the OS to execute. Before we had fancy visual interfaces, commands like create a file had to be typed out. While we have GUIs today, the shell is still commonly used to run commands, especially by power users. Power users are above average computer users. In Linux especially, it's essential that you actually know commands, not just a GUI. This is because most of the Linux machines you interact with in IT support, will be accessed remotely. Most of the time, you won't be given a GUI. There are lots of different types of shells. Some have different features, some handle performance differently, it's the same concept behind different operating systems. For our purposes, we'll just be using the most common shell, Bash or Bourne Again Shell in Linux. There's also a shelf for Windows called Powershell, but we won't be covering it here. You'll learn more about Windows power shell and the third course of this program. Operating systems and you becoming a power user. Throughout this program, we'll learn how to use the Windows GUI and Windows shell, Powershell. You might be thinking, but it's easier for me to navigate a GUI,than it is to use commands to do the same thing. So why would I want to learn both? I can't stress this enough, it's vital for you to know how to use a shell in an IT support role. Some tasks can only be completed through commands. In more advanced IT roles, you might have to manage thousands of machines. You don't want to have to click a button or drag a window on every machine when you can just run a command once. You're actually going to learn how to automate this in a later course. Using a GUI and shell isn't all you'll be doing, we'll also interact with our operating system through applications. There are system applications and libraries that we use on a day-to-day basis, like the log in application, system settings and more. Throughout this course, you learn more about how to use system applications. And we'll even get hands-on with the applications used in your operating system.