What's the USB Tablet option in Virtual box?

I would like to know what the USB Tablet option in Virtual Box means which comes under the System,Motherboard category as said here.

3 Answers

From the VirtualBox manual (Chapter 3.4.1):

The default virtual pointing devices for older guests is the traditional PS/2 mouse. If set to USB tablet, VirtualBox reports to the virtual machine that a USB tablet device is present and communicates mouse events to the virtual machine through this device.

and

Using the virtual USB tablet has the advantage that movements are reported in absolute coordinates (instead of as relative position changes), which allows VirtualBox to translate mouse events over the VM window into tablet events without having to "capture" the mouse in the guest. This makes using the VM less tedious even if Guest Additions are not installed.

Instead of simulating a mouse (which is a relative pointing device), it simulates an absolute pointing device. It offers several advantages/features:

• Accurate translation of cursor movement
• Pointer "integration" without additional guest-side software support
• Natively supported by modern operating systems

Earlier, VM software would pass on your relative mouse movements to the guest, where these movements could be subject to different acceleration and speed, depending on the guest OS settings. Also, because of these differences, it could not know where the pointer inside the guest is and required additional software to realize pointer integration.

By what I understand from the documentation, it basically makes the guest think there is a touchscreen connected. Also, there are usb devices which are about the size of a large tablet, with a stylus, that takes stylus presses and passes them as mouse events to the os, usually over usb I believe.