Open the virtual CD drive (often named "VirtualBox Guest Additions") and run VBoxWindowsAdditions.exe .

The Guest Additions are bundled with the VirtualBox installation and do not typically need to be downloaded separately . VBoxGuestAdditions.iso - virtualbox.org

Loading the vboxguestadditions module is a common rite of passage for any Linux user installing VirtualBox. Typically, it is compiled from source by the VirtualBox Guest Additions installer script, which builds it against the guest’s current kernel headers. This dynamic compilation ensures compatibility but also creates a dependency: after a Linux kernel update, the module must be rebuilt, or the guest will fall back to generic drivers. For end-users, this means re-running the "Insert Guest Additions CD image" menu option and executing the installer script. For system administrators, this process is often automated via package managers (e.g., the virtualbox-guest-utils package on Debian/Ubuntu) to ensure the module survives kernel updates.

Provides hardware 3D support (OpenGL and Direct3D) for smoother visual performance in Windows, Linux, and Solaris guests .