RHEL Red Hat Enterprise Linux
Red Hat's paid enterprise Linux. 10-year support per major version. The de-facto standard in larger companies, banks, governments.
Built on Fedora. Previously CentOS was a free 1:1 recompile of RHEL → Red Hat killed CentOS Linux in 2020 in favor of CentOS Stream (upstream for RHEL). Rocky Linux + AlmaLinux emerged as replacements. IBM-owned since 2019 (acquired for $34B). RHEL 9 (2022), RHEL 10 (2025). systemd + DNF + GNOME. Cost: ~$350–$3000/socket/year depending on support level.