Allows easy file sharing between the host and the guest OS.
By utilizing paravirtualized drivers (specifically for networking and storage), the Guest Additions reduce the overhead of hardware emulation. Instead of the CPU having to emulate the behavior of a specific physical network card, the guest driver communicates directly with the host network stack via optimized channels. vboxguestadditions
Open "My Computer" or "File Explorer" inside the Windows VM. Allows easy file sharing between the host and the guest OS