Oracle VM VirtualBox is a hosted virtualization product along the lines of VMware Player, Workstation and Fusion and Microsoft Virtual PC. But VirtualBox has some unique features and use cases of interest to server virtualization admins.
Oracle VM VirtualBox is a lightweight application that allows you to run virtual machines (VMs) on a variety of host operating systems. Following Oracle’s acquisition of Sun Microsystems, VirtualBox was officially renamed Oracle VM VirtualBox, and in February 2011, the company released version 4.0.4. VirtualBox is free and open source, but there’s also a free, closed source extension pack available with additional VirtualBox features.