Textbook of Linux

Red Hat Enterprise Linux (RHEL) is a commercial, enterprise-focused Linux distribution produced by Red Hat (now part of IBM). It is the polished, long-term-supported downstream of Fedora's work, sold with subscription-based support, certifications, and a stable 10-year lifecycle per major release. RHEL is the dominant Linux in the enterprise world, running on banks, governments, telcos, and most Fortune 500 companies.

RHEL's ecosystem includes the Red Hat stable itself, CentOS Stream (the upstream of future RHEL minor releases), and a family of RHEL-compatible rebuilds that rose after Red Hat ended the old CentOS project in 2020: Rocky Linux (community-run, founded by CentOS's original creator), AlmaLinux (community-run, backed by CloudLinux), and Oracle Linux (Oracle's own binary-compatible RHEL).

The RHEL technology stack has shaped mainstream Linux enormously: systemd, Anaconda installer, SELinux defaults, the Red Hat Package Manager (RPM) format, GNOME, and much more originated or were championed by Red Hat. Its deep investment in upstream kernel, glibc, gcc, and GNOME development makes it one of the largest contributors to open source globally.

For a home user, you would not typically run RHEL—you would run Fedora, CentOS Stream, Rocky, or Alma, all of which are free. RHEL's value is in the commercial support, compliance certifications, and long stability window that enterprises depend on.