@Pariah-Chan Typically when you run a computer it has an operating system running on it (say in this case for example, Windows). On other machines this may be different (the iPhone, Android Phones, PlayStation 3, PlayStation Portable, PlayStation Vita, PlayStation 4, PlayStation 5, Xbox 360, Xbox One, Xbox Series X, Nintendo DSi, Nintendo 3DS, Nintendo Wii, Nintendo Wii U, and Nintendo Switch for example all have their own "operating systems") but the general idea is still the same that these machines are made to run a particular operating system.
A virtual machine is when you take the power and resources of your operating system and push them to run a second operating system inside of it. There are number of reasons why this is handy and desirable and many of these are relatively practical purposes.
For example, these are the uses I would have for a virtual machine:
- A remote client so I can check the server status of a machine that's away from me (say for example logging onto a business/school network to do some work remotely).
- Running applications that aren't supported on your current operating system without needing to split your hard drive and reboot (such as installing Windows 95 to play DOS games)
- Securing an environment so you can do some work in a sandbox without risking your data being leaked (such as creating a Windows XP virtual machine to experiment with Windows XP's security)
- Protecting yourself from scammers who may try to infiltrate your machine and access your data (they cannot go "outside" of your virtual machine because it is a sandbox of its own so unless you bring something in they cannot leave it).
As I mentioned, there are many other uses for having a second or third (or multiple operating systems) installed on your machine with the ease of access like opening up an emulator/application without doing any restarting/rebooting (which is known as dual booting when you use two operating systems this way).
In the nature of the original thread, Sega's use of GameGuard prevents Phantasy Star Online 2 from working correctly under any other operating system. I have seen that Proton (Valve's implementation of WINE to allow Windows games to play on Linux which is very good for the most part) fails to run the game specifically because GameGuard cannot run correctly. If Phantasy Star Online 2 worked on Linux I would easily drop Windows as my primary environment due to my preference of Linux over Windows.