Q4OS
Q4OS is a light-weight Linux distribution, based on Debian, targeted as a replacement for operating systems that are no longer supported on outdated hardware. The distribution is known for an addon called XPQ4, which adds themes intended to replicate the look and feel of Windows 2000 and Windows XP. History 
Development of Q4OS began in 2014 to coincide with Windows XP's end of extended support in the same year. LXQt Desktop Environment was included from April 2014 to June 2015. In 2018 TDE (Trinity Desktop Environment) was included. In 2019, version 3.8 was released which was based on Debian Buster. The original KDE based version has been discontinued since around 2018. As of April 2020, the core developers of Q4OS, initially starting the project in Germany, are now operating in Prague, Czech Republic. Features 
It comes with either the Trinity Desktop Environment, which is a fork of K Desktop Environment 3. or KDE Plasma 5

LookSwitcher, which lets the user switch visual themes

Desktop Profiler, which automatically installs some packages and programs that may be ideal for the user according to the profile that they choose

Q4OS Software Centre, which lets the user install some recommended packages and programs from a list

Q4OS Welcome Screen, which helps the user with some initial tweaks

Releases 
Stable versions of Q4OS are derived from Debian's Stable release branch with long-term support that lasts five years after their initial release. Developmental "testing" versions of future releases are derived from the Debian Testing branch. Reception 
SourceForge featured Q4OS as "Community Choice" Project of the Month in April 2020. In January 2022, TechRadar considered Q4OS as one of the best light-weight Linux distributions of the year for its Windows installer and support for older hardware, notably systems running on 32-bit processors. Forks

Quarkos 
Quarkos (formerly known as Quark) is an official fork of Q4OS that uses an Ubuntu base instead of Debian. It describes itself as a 'user-friendly, desktop oriented operating system based on Ubuntu Linux'. It comes in two variants, one of which uses the same desktop theme as Q4OS, while the other uses a visual theme similar to Windows 10. Quark 20.04 
Quark 20.04 'Focal' was the first release, coming with the same base as Ubuntu 20.04. It was released on the September 25th 2020, featuring only the KDE Plasma 5 desktop. On November 3, 2020, the development team announced that Microsoft Edge was now available for Linux, and users of Quark would be able to install it by downloading a .esh file from the Q4OS GitHub repository. Quark 20.04.4, released September 24, 2021 added bugfixes from upstream Kubuntu. On October 9, 2021, the development team announced the general availability of the Windows installer for Quark 20.04 Focal. Quark 20.04.5 was made available on November 28, 2021, bringing bugfixes from Kubuntu and Trinity desktop environment R14.0.11. An updated version of the Quark installer for windows was released on February 2, 2022. Quark 20.04.6 brought security bugfixes from upstream Kubuntu. Quark 21.10 
Quark 21.10 'Impish' testing was announced on October 9, 2021, based on Kubuntu 21.10 and tools backported from Q4OS 4 'Gemini'. It was released with a stable version on October 18, 2021, with KDE Plasma 5.22 by default and the Windows and Q4OS themed variants. It also came with another edition with the Trinity 14.0.11 desktop backported from Q4OS. Quark 21.10 was supported until August 2, 2022, following the end of support for Ubuntu 21.10. Quarkos 22.04 
Quarkos 22.04 'Jammy' was released on August 24, 2022, based on Ubuntu 22.04 LTS and Plasma 5.24. It will be supported until at least April 2027. Quarkos 22.04 changes the branding from simply Quark to Quarkos, bringing separate installation media for the Trinity desktop, which has been updated to R14.0.12, but with the KDE Plasma edition as the default. Quarkos 22.04.5 and 22.04.6 were released on December 29, 2022 and February 27, 2023 respectively, each bringing security updates and bugfixes from upstream Ubuntu. Quarkos 22.04.7 was released on March 19, 2023, and brought updates from the latest release of Ubuntu 22.04. It also replaced much of the Q4OS branding with its own, including artwork, logos and branding integrated into the system. The source code was made available on the Q4OS project GitHub. Quarkos 22.04-r8, released on June 23, 2023, brought the newest patches from Ubuntu 22.04 and Q4OS. It improves the Debonaire Plasma theme, updates the Trinity Desktop Environment to version 14.1.1 and includes fixes for the Trinity audio system. FreeXP 
FreeXP is a system based Q4OS which included XPQ4. Users can set up the system using a .esh file to install the full set of features, or a live installer with the changes already made. The purpose of the project is to provide an 'XP Simulation', similar to how FreeDOS emulates MS-DOS, making it easy to run legacy Windows XP applications and executables. The standalone project has merged with the XPQ4 project, where users can download FreeXP, XPQ4 installer for the Plasma or Trinity desktop, and 'Free10', a project similar to FreeXP but emulating Windows 10. See also 
 Comparison of light-weight Linux distributions
 Trinity Desktop Environment
 ReactOS
 Linux XP

References

External links 
 
 
 Q4OS and TDE: A Juicy Little Linux Secret

IA-32 Linux distributions
X86-64 Linux distributions
Linux distributions
Debian-based distributions