Book excerpt: AlmaLinux 9 Essentials is intended to provide detailed information on the installation, use, and administration of the AlmaLinux 9 distribution. For beginners, the book covers topics such as operating system installation, the basics of the GNOME desktop environment, configuring email and web servers, and installing packages and system updates. Additional installation topics, such as dual booting with Microsoft Windows, are also covered, together with all important security topics, such as configuring a firewall and user and group administration. For the experienced user, topics such as remote desktop access, the Cockpit web interface, logical volume management (LVM), disk partitioning, swap management, KVM virtualization, Secure Shell (SSH), Linux Containers, and file sharing using both Samba and NFS are covered in detail to provide a thorough overview of this enterprise class operating system.