Oracle VM VirtualBox is a free and open-source sandbox type environment for x86 computers allowing you to install and load multiple guest OSs under a single host operating-system, each guest can be started, paused and stopped independently within its own virtual machine. The user can independently configure each virtual machine and run it under a choice of software-based virtualization or hardware assisted virtualization providing that the underlying host hardware supports it. The host OS and guest OSs and applications can communicate with each other through a number of mechanisms including a common clipboard and a virtualized network facility. Guest virtual machine can also directly communicate with each other if configured to do so. For more information visit the VirtualBox Information page.
1.) Update System.
As always you should make sure that your system is up to date before attempting to install something new. This helps to keep you away from annoying errors only to find out your system just needed updated. Open the Terminal (CTRL+ALT+t) and use this command, followed by your password.
$ sudo apt-get update && sudo apt-get upgrade
2.) Download Key.
Download and install the Oracle public key with this command.
$ wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox_2016.asc -O- | sudo apt-key add -
3.) Add The PPA.
Now you can add it to the PPA to your source list.
$ sudo sh -c 'echo "deb http://download.virtualbox.org/virtualbox/debian $(lsb_release -cs) contrib" >> /etc/apt/sources.list.d/virtualbox.list'