The following is a brief outline of Oracle VM VirtualBox's main features:
Portability. Oracle VM VirtualBox runs on a large number of 64-bit host OSes. See Section 1.4, “Supported Host Operating Systems”.
Oracle VM VirtualBox is a so-called hosted hypervisor, sometimes referred to as a type 2 hypervisor. Whereas a bare-metal or type 1 hypervisor would run directly on the hardware, Oracle VM VirtualBox requires an existing OS to be installed. It can thus run alongside existing applications on that host.
To a very large degree, Oracle VM VirtualBox is functionally identical on all of the host platforms, and the same file and image formats are used. This enables you to run virtual machines created on one host on another host with a different host OS. For example, you can create a virtual machine on Windows and then run it under Linux.
In addition, virtual machines can easily be imported and exported using the Open Virtualization Format (OVF), an industry standard created for this purpose. You can even import OVFs that were created with a different virtualization software. See Section 1.14, “Importing and Exporting Virtual Machines”.
No hardware virtualization required. For many scenarios, Oracle VM VirtualBox does not require the processor features built into current hardware, such as Intel VT-x or AMD-V. As opposed to many other virtualization solutions, you can therefore use Oracle VM VirtualBox even on older hardware where these features are not present. See Hardware vs. Software Virtualization.
Guest Additions: shared folders, seamless windows, 3D virtualization. The Oracle VM VirtualBox Guest Additions are software packages which can be installed inside of supported guest systems to improve their performance and to provide additional integration and communication with the host system. After installing the Guest Additions, a virtual machine will support automatic adjustment of video resolutions, seamless windows, accelerated 3D graphics and more. See Chapter 4, Guest Additions.
In particular, Guest Additions provide for shared folders, which let you access files on the host system from within a guest machine. See Section 4.3, “Shared Folders”.
Great hardware support. Among other features, Oracle VM VirtualBox supports the following:
Guest multiprocessing (SMP). Oracle VM VirtualBox can present up to 32 virtual CPUs to each virtual machine, irrespective of how many CPU cores are physically present on your host.
USB device support. Oracle VM VirtualBox implements a virtual USB controller and enables you to connect arbitrary USB devices to your virtual machines without having to install device-specific drivers on the host. USB support is not limited to certain device categories. See Section 3.11.1, “USB Settings”.
Hardware compatibility. Oracle VM VirtualBox virtualizes a vast array of virtual devices, among them many devices that are typically provided by other virtualization platforms. That includes IDE, SCSI, and SATA hard disk controllers, several virtual network cards and sound cards, virtual serial and parallel ports and an Input/Output Advanced Programmable Interrupt Controller (I/O APIC), which is found in many computer systems. This enables easy cloning of disk images from real machines and importing of third-party virtual machines into Oracle VM VirtualBox.
Full ACPI support. The Advanced Configuration and Power Interface (ACPI) is fully supported by Oracle VM VirtualBox. This enables easy cloning of disk images from real machines or third-party virtual machines into Oracle VM VirtualBox. With its unique ACPI power status support, Oracle VM VirtualBox can even report to ACPI-aware guest OSes the power status of the host. For mobile systems running on battery, the guest can thus enable energy saving and notify the user of the remaining power, for example in full screen modes.
Multiscreen resolutions. Oracle VM VirtualBox virtual machines support screen resolutions many times that of a physical screen, allowing them to be spread over a large number of screens attached to the host system.
Built-in iSCSI support. This unique feature enables you to connect a virtual machine directly to an iSCSI storage server without going through the host system. The VM accesses the iSCSI target directly without the extra overhead that is required for virtualizing hard disks in container files. See Section 5.10, “iSCSI Servers”.
PXE Network boot. The integrated virtual network cards of Oracle VM VirtualBox fully support remote booting using the Preboot Execution Environment (PXE).
Multigeneration branched snapshots. Oracle VM VirtualBox can save arbitrary snapshots of the state of the virtual machine. You can go back in time and revert the virtual machine to any such snapshot and start an alternative VM configuration from there, effectively creating a whole snapshot tree. See Section 1.10, “Snapshots”. You can create and delete snapshots while the virtual machine is running.
VM groups. Oracle VM VirtualBox provides a groups feature that enables the user to organize and control virtual machines collectively, as well as individually. In addition to basic groups, it is also possible for any VM to be in more than one group, and for groups to be nested in a hierarchy. This means you can have groups of groups. In general, the operations that can be performed on groups are the same as those that can be applied to individual VMs: Start, Pause, Reset, Close (Save state, Send Shutdown, Poweroff), Discard Saved State, Show in File System, Sort.
Clean architecture and unprecedented modularity. Oracle VM VirtualBox has an extremely modular design with well-defined internal programming interfaces and a clean separation of client and server code. This makes it easy to control it from several interfaces at once. For example, you can start a VM simply by clicking on a button in the Oracle VM VirtualBox graphical user interface and then control that machine from the command line, or even remotely. See Section 1.16, “Alternative Front-Ends”.
Due to its modular architecture, Oracle VM VirtualBox can also expose its full functionality and configurability through a comprehensive software development kit (SDK), which enables integration of Oracle VM VirtualBox with other software systems. See Oracle VM VirtualBox Programming Interfaces.
Remote machine display. The VirtualBox Remote Desktop Extension (VRDE) enables high-performance remote access to any running virtual machine. This extension supports the Remote Desktop Protocol (RDP) originally built into Microsoft Windows, with special additions for full client USB support.
The VRDE does not rely on the RDP server that is built into Microsoft Windows. Instead, the VRDE is plugged directly into the virtualization layer. As a result, it works with guest OSes other than Windows, even in text mode, and does not require application support in the virtual machine either. The VRDE is described in detail in Remote Display (VRDP Support).
On top of this special capacity, Oracle VM VirtualBox offers you more unique features:
Extensible RDP authentication. Oracle VM VirtualBox already supports Winlogon on Windows and PAM on Linux for RDP authentication. In addition, it includes an easy-to-use SDK which enables you to create arbitrary interfaces for other methods of authentication. See RDP Authentication.
USB over RDP. Using RDP virtual channel support, Oracle VM VirtualBox also enables you to connect arbitrary USB devices locally to a virtual machine which is running remotely on an Oracle VM VirtualBox RDP server. See Remote USB.