An article written by Ravi Saive, published in tecmint magazine explains, how to install recently released VirtualBox 5.0, in different GNU/Linux distributions like RHEL, CentOS, Fedora, Debian, Ubuntu and Linux Mint.
VirtualBox is an open source cross-platform virtualization software, it can be installed on any operating system and enable you to install and run multiple guest operating systems on same computer. For example, if you install it on your Linux system, you can run Windows XP operating system under it as a Guest OS or run Linux OS on your Windows system and so on. This way, you can install and run as many as guest operating systems as you like, the only limit is disk space and memory.