VirtualBox Guest Additions
VirtualBox guest additions usually focus on a few aspects of the virtual machine's performance.
Mouse pointer integration is usually enabled with a guest addition. In most virtual machine environments, when you move the mouse pointer from your host operating system into the guest operating system's window, you have to click inside of that window to switch focus. Seamless mouse pointer integration allows you to work within the virtual machine window without having to capture and release the mouse pointer.
Improved video support is also offered by guest additions. The basic video card support in VirtualBox allows for basic features. However, many operating systems (including Windows 7 and some distributions of Linux) use window environments that have much more visually-appealing designs. Additionally, higher resolutions can be achieved by using guest additions.
In order to share folders and share the system clipboard between machines, guest additions must be installed. Sharing folders allows you to transfer files from the host operating system to the guest operating system, or vice-versa.
Finally, VirtualBox guest additions provides support for seamless windows for some operating systems. Seamless windows allows you to pull the guest operating system environment out of the virtual machine window. The guest operating system's windows can move freely among your host operating machine's windows.