Virtualization is a powerful paradigm of computing and software engineering. It permits to run different systems on the same machine. One of these products is VirtualBox, a powerful x86 virtualization tool that can be used both for enterprise and home purposes. It gives the possibility to run different OS host like Macintosh, Windows, and Linux. Moreover, it supports a number of guest OS including but not limited to Windows (XP, Server 2003, Vista), Linux (2.4 and 2.6), and OpenBSD. It is one of the few professional products that is freely available as Open Source Software under the terms of the GPL License. You don't have to pay to virtualize your systems, with VirtualBox it's just easy and free!

Exporting VM descriptions
Virtual machines can be exported in XML format, therefore being independent of local machines. Virtual machine definitions can be easily exported to other computers and this makes configuration of large networks very easy.

Guest Additions for Windows and Linux
VirtualBox has powerful features that can improve performance and make integration much more seamless. Among the features provided by these Guest Additions are mouse pointer integration and arbitrary screen solutions. You don't have to purchase additional products to have a complete Virtualization framework.

Shared folders among guest and host
Like many other virtualization solutions, for easy data exchange between hosts and guests, VirtualBox allows for declaring certain host directories as "shared folders", which can then be accessed from within virtual machines.

Modular Structure
VirtualBox has a modular client/server design with several programming interfaces. It comes with a full SDK: even though it is Open Source Software, you don't have to hack the source to write a new interface for it.