A PKG.TAR.XZ file is a package file used by pacman, a package manager included with Arch Linux and Arch Linux based operating systems (OS). It contains binary files and installation instructions used by pacman for installing software.

The PKG.TAR.XZ file consists of a software package stored in a .TAR archive that has been compressed using .XZ compression, which allows the software package file to be more easily distributed. The PKG file contains software that is installed in the Arch Linux distribution using Pacman, a package manager that assists in the installation, upgrading, configuring, and removing of computer software. Pacman includes tools such as makepkg, pactree, checkupdates, and vercmp. PKG.TAR.XZ files are created when the makepkg utility is run, which compiles software installation files into a PKG.TAR.XZ file. NOTE: Arch Linux is a Linux distribution first released in 2002. It is designed for computers based on i686 and x86-64 architectures.