The VirtualBox package installs on an existing host operating system as an application; this host application allows additional guest operating systems, each known as a Guest OS, to load and run, each with its own virtual environment.
Supported host operating systems include Linux, Mac OS X, Windows XP, Windows Vista, Windows 7, Windows 8, Solaris, and OpenSolaris; there are also ports to FreeBSD and Genode.
Supported guest operating systems include versions and derivations of Windows, Linux, BSD, OS/2, Solaris, Haiku and other Since release 3.2.0, VirtualBox also allows limited virtualization of Mac OS X guests on Apple hardware, though OSX86 can also be installed using VirtualBox.
Since version 4.3 (released in October 2013), Microsoft Windows guests on supported hardware can take advantage of the recently implemented WDDM driver included in the guest additions; this allows Windows Aero to be enabled along with Direct3D support.
Guest Additions should be installed in order to achieve the best possible experience.The Guest Additions can be installed inside a virtual machine after the installation of the guest operating system. They consist of device drivers and system applications that optimize the guest operating system for better performance and usability.