Since you found your way here, you probably have a basic understanding of Linux but perhaps not some critical details. If you have a Linux distribution already, you can just use it. You don’t have to read anymore but this article can help you understand what makes Linux different from other operating systems (OSes).
At its most basic level, Linux is a kernel, the core part of the OS that communicates between software (including the OS outside the kernel) and hardware at a very basic level. It’s the traffic controller. The Linux kernel was created by Linus Torvalds in 1991.
Alone, a kernel doesn’t do much, you need a graphical user interface (GUI), file management, a backup program and other utilities such as picture, audio and video viewers. And with Linux, a terminal program. These basics along with the kernel form the OS. Sometimes the OS contains more than these basics such as Microsoft bundling a malware scanner and web browser with Windows.
Early on, Linus needed very basic programs and a base to build on and found it in the GNU project which had most of what was needed for an OS except a kernel. Hence, Linux was often referred to as GNU/Linux. It still uses GNU today but relies on it to a much lesser extent.
On top of the OS, you have other software, often essential, such as web browsers, office suites, and communication software such as Zoom. The separation between the OS and the programs running on it can be blurred. That’s because you don’t normally get just the OS. Linux comes with the base OS plus extra software. These variants are called distributions.
Unlike with Windows or Mac OS, you also have a choice of GUI (also called a desktop environment) with its own file managers, viewers and other utilities. The most popular are Gnome and Plasma (often referred to as KDE, the organization that makes it) but Cinnamon, MATE and Xfce are others and are widely used. Distributions usually have a default desktop environment. For example, Ubuntu uses Gnome in their distro (distribution). But there are variants of Ubuntu that have the underlying Linux OS with different desktop environments such as Plasma, MATE or Cinnamon.
Some popular distributions are Ubuntu Desktop, OpenSUSE Leap, and Linux Mint. With some exceptions, Linux distributions have the same vast catalogue of software no matter what distribution you settle with. They just install with a certain set of programs that you can add to (and will). Sometimes it’s confusing but that’s what it means to have more choice. Linux can look the way you want it to and work the way you want it to. That’s why Linux User Groups (LUGs) exist, to help each other get settled into the Linux world and share our knowledge. We hope you can help you in your exploration.