With all the different desktop environments available for Linux, your options are endless. In the Linux world, we have GNOME, Cinnamon, Xfce, MATE, Pantheon, Unity, Openbox, KDE, and others from which you can choose. The benefit is that if you don't like one interface, you can use another, though finding your favorite can take a bit of research.
The K Desktop Environment (KDE) has been around for quite a while and is actually one of the oldest of the Linux graphical environments. It largely competed with the GNOME desktop in the early days, and for the most part, the decision of which user interface to install basically revolved around those two environments. Back then, the GNOME desktop largely resembled the user interface used by Mac while KDE looked closer to Windows. However, today, GNOME doesn't resemble the Macintosh platform anymore, and KDE has also developed an aesthetic of its own. Even today, many debates on the "best" desktop environment often still revolve around GNOME or KDE, though there are, of course, other contenders nowadays, such as Cinnamon.
While initially KDE was an all-inclusive term to describe its desktop environment as a whole, the software has since been componentized. Now, KDE is known as KDE SC (KDE Software Compilation) which consists of the Plasma Workspace (the desktop/interface layer) and KDE Applications (a suite of applications to run on the Plasma Workspace).
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As the terminology has become confusing, most Linux users still refer to the software generally as KDE. It's unlikely that you'll hear KDE SC referred to as anything other than just simply KDE in the wild. Although the official name has changed, it has yet to catch on.
The KDE edition of Linux Mint doesn't adhere to the same Mint-X theme that is used in all other versions of Mint. This means that instead of the green icons and colors you may be used to, the KDE edition takes on a blue color scheme instead. This is in line with how KDE is by default, as the Mint developers haven't changed the look and feel as much as they have with other versions. The reason for this is because KDE is designed around the Qt toolkit, which uses a completely different theme style than GTK, which is what Cinnamon, Xfce, and MATE use.
In order to port Mint's theme to KDE, it would have required a fair amount of reengineering. So, much of the default KDE theme has been left as it is, though some minor customizations (such as the wallpaper) have been added. Another difference with Mint's implementation of KDE is that you open icons by double-clicking on them rather than a single-click as in most KDE-based distributions. The following screenshot shows Linux Mint KDE's default desktop:
KDE's Application Launcher, which is almost always the icon on the far left of the panel, is split into sections such as Favorites, Applications, Computer, and Recently Used. To start an application, you move to the Applications tab, find the program you want to launch, and click on it. You can also find applications by typing into the search box at the top of the Application Launcher. The following screenshot shows KDE's Application Launcher:
If you want to add an application to Favorites, simply right-click on the application and click on Add to favorites. From that point forward, that application will be available on the Favorites tab (the first section) for easy access. The Recently Used tab lists files/locations that you've opened recently. The Applications tab shows all the applications available on your system, which are categorized so that you can find them easily.
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The Application Launcher icon in Mint's implementation has the letters "lm" over a gear. In most other versions, the Application Launcher is a "K" icon instead. Other than the different icon, the Application Launcher in Mint's implementation is the same as in other KDE distributions.
Moving on, the next item visible in the KDE edition's panel is the Show Desktop icon, which does exactly as its name suggests. If you click on it, all windows are minimized. If you click on it again, the windows that were minimized will reappear. Next, there's an icon to launch Dolphin, which we'll get to in the next section.
On the right-hand side of KDE's panel, you'll find icons that display the status of system components (such as networking and audio volume) as well as the date/time. Clicking on Kmix (the volume control icon) will allow you to adjust the volume, whereas right-clicking on it will allow you to edit more advanced sound settings. The Network Manager icon will display either a wired icon or a wireless icon depending on your network connection, and this will be discussed in greater detail later in this appendix.
In the middle of the panel is where your running applications will be listed. The style of showing applications in KDE is very similar to Windows; so, if you've used Windows, then you'll immediately be familiar with the concept.