Red Hat Enterprise Linux (RHEL)

RHEL is Red Hat's flagship commercial product: a long-life-cycle (typically 10 years of support per major version), rigorously certified distribution that hardware vendors, ISVs, and enterprise software all test and certify against first. Its source code is public under the GPL, which is exactly what makes 'RHEL-compatible' rebuilds like Rocky Linux and AlmaLinux legally possible -- they take Red Hat's published sources and rebuild them without the trademark or paid support contract. Red Hat funds and steers Fedora as RHEL's upstream testing ground, meaning features generally appear in Fedora years before landing in a RHEL release. A free, self-support developer subscription (up to 16 systems) is available directly from Red Hat for individual and small-scale use.