Fedora Linux

The fourth one is Fedora Linux.

Fedora is an operating system based on the Linux kernel, developed by the community-supported Fedora Project and sponsored by Red Hat. Fedora contains software distributed under a free and open source license and aims to be on the leading edge of such technologies.
Linus Torvalds, creator of the Linux kernel, uses Fedora on all of his computers.

Fedora has a reputation for focusing on innovation, integrating new technologies early on and working closely with upstream Linux communities. Making changes upstream instead of specifically in Fedora ensures that the changes are available to all Linux distributions.
Fedora has a relatively short life cycle: version X is supported only until 1 month after version X+2 is released and with approximately 6 months between most versions, meaning a version of Fedora is usually supported for approximately 13 months. Fedora users can upgrade from version to version without reinstalling.
The default desktop in Fedora is GNOME desktop environment and the default interface is the GNOME Shell. Other desktop environmnets, including KDE, Xfce, LXDE, MATE and Cinnamon, are available and can be installed.
Fedora uses the RPM package system.
Security is also important in Fedora with one specific security feature being Security-Enhanced Linux, which implements a variety of security policies, including mandatory access constrols, and which Fedora adopted early on.

The Fedora Project's mission is to lead the advancement of free and open source software and content as a collaborative community.
The three elements of this mission are clear:
- The Fedora Project always strives to lead, not follow
- The Fedora Project consistently seeks to create, improve, and spread free/libre code and content
- The Fedora Project succeds through shared action on the part of many people throughout their community

Pros:
- Fedora is not as difficult to configure or maintain as Debian or Arch
- Fedora has an excellent community in terms of user support
- Fedora is known for high quality and advanced functions without the instability of versions like Arch
- Fedora is open source
- Fedora does not have all the Amazon ads

Cons:
- Mint or Ubuntu are easier to configure or maintain
- no backward compatibility
- hard to find device drivers

References:
1. https://wikipedia.org
2. https://fedoraproject.org