Virtual Box

ORACLE VM VirtualBox

To extends the capabilities of your existing computer so that it can run multiple operating systems (inside multiple virtual machines) at the same time. So, for example, you can run Windows and Linux on your Mac, run Windows Server 2008 on your Linux server, run Linux on your Windows PC, and so on, all alongside your existing applications. You can install and run as many virtual machines as you like – the only practical

limits are disk space and memory.

Why is virtualization useful?

• Running multiple operating systems simultaneously.
• Easier software installations.
• Testing and disaster recovery.
• Infrastructure consolidation.    

Some Terminology

• Host operating system (host OS).
• Guest operating system (guest OS).
• Virtual machine (VM).
• Guest Additions.

Source