QEMU is a free and open-source machine emulator and virtualizer that can run operating systems and programs made for one machine on a different machine. QEMU is available for a variety of operating systems including Linux, Windows, and macOS. QEMU can also be used as a machine emulator, allowing users to run virtual machines with different operating systems on a single physical machine.

qemu-img is a command-line tool that is used to create, convert, and modify disk image files that can be used with QEMU. Disk images are used to store the contents of a hard drive, CD-ROM, or other storage medium in a single file that can be easily transferred between systems or used to create virtual machines.

One of the key benefits of using qemu-img is its flexibility. It can be used to create disk images in a variety of formats, making it easy to work with different virtualization solutions and operating systems. qemu-img can also be used to clone and copy disk images, which is useful for creating backup copies of VMs or deploying new VMs from existing disk images. Additionally, qemu-img provides a variety of options and settings that allow users to customize the disk images they create to suit their needs.