How to run multiple operating systems on your computer?

Yes, It is exactly how it is written in the title, we'll discover more in this article. 
If you didn't know, Running multiple operating systems on the same computer you are reading this from now is possible, not talking about dual booting, but it's like having multiple computers, using the same hardware and running different Operating systems, you can use this in many cases, for example: if you wanna try a new OS but not on your physical computer not wanting to keep fixing later, just throw it in the virtual machine  and if it doesn't work, simply delete the machine, you can test out softwares to be more secure and not infecting your own computer, this comes handy in many cases.
the program that will help us achieve this is VirtualBox you can download it from the official link, it's available for almost all the Systems, and is more likely to work on the system you are using now. it's easy to use, after installing Virtualbox, create a new virtual machine from the button, keep clicking on next with the recomended settings, after choosing how much ram you want your machine to use, video memory and disk space, you choose the ISO image to install it. you can have as much machines as you want, we also have VMware, but virtualbow is free, and as good.