Linux is a family of free and open-source software operating systems built around the Linux kernel. Typically, Linux is packaged in a form known as a Linux distribution for both desktop and server use.
The majority of popular Linux distributions are based on the Linux kernel and support common desktop and server software applications out of the box. This makes Linux an attractive choice for both individuals and organizations looking for an alternative to more expensive, proprietary operating systems.
A Linux distribution (often abbreviated as distro) is an operating system made from a software collection, which is based upon the Linux kernel and, often, a package management system. A typical Linux distribution includes a large number of software applications such as text editors, media players, and office applications, which are all provided by separate software packages. Most distributions also include a package manager which automates the process of installing, upgrading, and removing software packages.
The vast majority of distributions use the GNU General Public License (GNU GPL) which, following the lead of the Linux kernel, allows anyone to create, modify, and redistribute the software, either in whole or in part, for free.
A notable exception to this rule is Apple's macOS, which uses a mixture of open source components (such as the Darwin kernel) and propriety components, and is only available directly from Apple.
Linux system administration is the process of managing a Linux system, including installing, configuring, and maintaining the various software components that make up the system. System administrators are responsible for ensuring that the system is up to date, secure, and running efficiently.
While Linux is generally very stable and easy to use, it is important to have some basic understanding of how the system works in order to be able to troubleshoot problems when they arise. For this reason, it is recommended that new Linux users take some time to learn the basics of the system before embarking on more complex tasks.
Learning Linux system administration can be a challenging and time-consuming task, but it is a necessary skill for anyone who wants to be able to use and maintain a Linux system. Some of the topics that a Linux system administrator should be familiar with include installing and configuring Linux, managing users and groups, managing file permissions, working with the Linux command line, and managing software packages.