Hi there!
I think what you are looking for is what they call a Virtual Machine. A Virtual Machine (e.g. Virtual Box, etc...) is a program where you can run a separate OS on your computer without changing the current OS of your computer. For example, if the current OS of your PC is Windows you can run a Mac OS through the Virtual Machine at the same time as running Windows. The hardware you need for this is a disk of a drive to download the OS on to the Virtual Machine, the software is the Virtual Machine program, and the operating system environment is what you run on the Virtual Machine program.
-ASIAX Frequent Answerer
