Red Hat Enterprise Linux in the context of Red Hat

Linux (/ˈlɪnʊks/ LIN-uuks) is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution (distro), which includes the kernel and supporting system software and libraries—most of which are provided by third parties—to create a complete operating system, designed as a clone of Unix and released under the copyleft GPL license.

Thousands of Linux distributions exist, many based directly or indirectly on other distributions; popular Linux distributions include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while commercial distributions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are frequently used in server platforms. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses and recommends the name "GNU/Linux" to emphasize the use and importance of GNU software in many distributions, causing some controversy. Other than the Linux kernel, key components that make up a distribution may include a display server (windowing system), a package manager, a bootloader and a Unix shell.

Linux on IBM Z, Linux on zSystems, or zLinux is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z, zSystems, and LinuxONE servers. Similar terms which imply the same meaning are Linux/390, Linux/390x, etc. The three Linux distributions certified for usage on the IBM Z hardware platform are Red Hat Enterprise Linux, SUSE Linux Enterprise Server, and Ubuntu.

A Linux distribution, often abbreviated as distro, is an operating system that includes the Linux kernel for its kernel functionality. Although the name does not imply product distribution per se, a distro—if distributed on its own—is often obtained via a website intended specifically for the purpose. Distros have been designed for a wide variety of systems ranging from personal computers (for example, Linux Mint) to servers (for example, Red Hat Enterprise Linux) and from embedded devices (for example, OpenWrt) to supercomputers (for example, Rocks Cluster Distribution).

A distro typically includes many components in addition to the Linux kernel. Commonly, it includes a package manager, an init system (such as systemd, OpenRC, SysVinit, or runit), GNU tools and libraries, documentation, IP network configuration utilities, the getty TTY setup program, and many more. To provide a desktop experience (most commonly the Mesa userspace graphics drivers) a display server (the most common being the X.org Server, or, more recently, a Wayland compositor such as Sway, KDE's KWin, or GNOME's Mutter), a desktop environment (most commonly GNOME, KDE Plasma, or Xfce), a sound server (usually either PulseAudio or more recently PipeWire), and other related programs may be included or installed by the user.

Fedora Linux is a free and open-source Linux distribution developed by the Fedora Project. It was originally developed in 2003 as a continuation of the Red Hat Linux project. It contains software distributed under various free and open-source licenses and aims to be on the leading edge of open-source technologies. It is now the upstream source for CentOS Stream and Red Hat Enterprise Linux.

Since the release of Fedora 21 in December 2014, three editions have been made available: personal computer, server and cloud computing. This was expanded to five editions for containerization and Internet of Things (IoT) as of the release of Fedora 37 in November 2022. A new version of Fedora Linux is released every six months.

XFS is a high-performance 64-bit journaling file system created by Silicon Graphics, Inc (SGI) in 1993. It was the default file system in SGI's IRIX operating system starting with its version 5.3. XFS was ported to the Linux kernel in 2001; as of June 2014, XFS is supported by most Linux distributions; Red Hat Enterprise Linux uses it as its default file system.

XFS excels in the execution of parallel input/output (I/O) operations due to its design, which is based on allocation groups (a type of subdivision of the physical volumes in which XFS is used – also shortened to AGs). Because of this, XFS enables extreme scalability of I/O threads, file system bandwidth, and size of files and of the file system itself when spanning multiple physical storage devices. XFS ensures the consistency of data by employing metadata journaling and supporting write barriers. Space allocation is performed via extents with data structures stored in B+ trees, improving the overall performance of the file system, especially when handling large files. Delayed allocation assists in the prevention of file system fragmentation; online defragmentation is also supported.