There are many more operating systems you can install as virtual machines in VirtualBox. Windows, other Linux distributions, and virtual appliances are all available and are only limited by your research needs. I happen to like to run Windows Desktop as a virtual machine for research purposes, along with Kali Linux when I perform penetration assessments. Having both as virtual machines allows me to quickly revert back to previously saved snapshots, which we will cover later in this chapter, in order to start from a clean slate for the next penetration assessment I need to perform. I recommend doing this so that you always have a clean virtual machine to revert back to in the event something goes wrong while you're analyzing binaries or upgrading the operating system.