GNOME Boxes is an application of the GNOME Desktop Environment, used to access remote or virtual systems. Boxes uses the QEMU, KVM, and libvirt virtualization technologies.
GNOME Boxes requires the CPU to support some kind of Hardware-assisted virtualization (Intel VT-x, for example).
Kernel-based Virtual Machine (KVM) is a virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the Linux kernel mainline in kernel version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.