Oracle VM VirtualBox is an industrial-strength open source virtualisation tool that makes it easy to create virtual machines (VMs), simulated computers that run on your PC but act as though they were separate systems. It's a powerful capability that has many different applications.
If you'd like a closer look at Windows 8 before you upgrade, for instance, then you could install Microsoft's latest in a VM, then access it in a window on your XP or Vista desktop.
Or maybe you've upgraded to Windows 8 and find a favourite old app doesn't work any more? Create a Windows XP VM and you might be able to run it again.
VirtualBox can also be a useful security tool: if you download and test apps in a VM, then any malware you might encounter will be isolated from your main system.
And it's the perfect choice if you want to try out another operating system with the minimum of hassle. Right now you can install Google Chrome OS, all the mainstream Linux variants (2.4 and 2.6), OpenBSD, OS/2, ReactOS, SkyOS, DOS, and just about every version of Windows there's ever been. (Of course you'll need to have the system discs to hand.)
VirtualBox 4 included an interface redesign, making it easier to view and manage your virtual machines. VM displays can now be scaled, so you can reduce a window size by half (for instance) and still see everything that's going on. The ability to limit a VM's CPU and IO time means the program will be less of a drain on your system's resources, and there are a host of other performance optimisations and bug fixes available.
What's new in VirtualBox 5?
- VMM: fixed a problem which could lead to a wrong guest behavior on AMD CPUs (tickets #14831 and #15186)
- GUI: don't try to synchronize the HID LEDs if the VM window is not active or if it's minimized (Windows / Mac OS X hosts only; bug #14302)
- GUI: prevent a crash during startup under rare conditions
- GUI: sub-menu option to disable the guest-OS type overlay in the application dock icon on Mac OS X
- GUI: position off-screen windows to be fully visible again on relaunch
- GUI: hide the VT-x/AMD-V checkbox if raw-mode is not supported (usually Mac OS X hosts; bug #15178)
- PC speaker passthrough: new experimental feature, available on Linux host only
- Audio: several fixes for Mac OS X hosts + guests
- Audio: properly handle default audio device changes (Windows hosts)
- USB: serveral fixes for the xHCI controller (e.g. for webcam passthrough)
- BIOS: fixed int15/AH=83/AL=00 function (4.2.0 regression)
- iPXE: enable the HTTP download protocol on non-Linux hosts (bug #13628)