Virtual Machine
Program
Wikipedia
A software and/or hardware system that emulates the hardware of a certain platform and executes programs for a guest platform on a host platform or virtualizes a certain platform and creates environments on it that isolate programs and even operating systems from each other; also a specification of a certain computing environment.

How do I create a virtual machine?
To create a virtual machine, click the button or select the menu item: "Machine-create" or press the keyboard shortcut Ctrl+N. In the window that opens (Figure 13), we set the name of the virtual system, the type and version of the guest operating system. My virtual machine will be called "VM"

How do I install a VM?
To do this, you need to do the following: Launch VirtualBox and in the right part select "Create" In the window that appears, enter the name of the operating system and specify the path to the machine, Select how much RAM will be allocated for the future OS

What is a virtual operating system?
Virtual Operating system − this is an operating system installed on a virtual machine. You can install any system on the virtual machine that you can install on your computer and that is supported by the software used for virtualization.

What is a virtual machine?
A virtual machine is a program that emulates a computer system in isolation from other software on the same computer system, in simple terms.

Which OS is on the virtual machine?
Operating systems such as Linux, Windows, Solaris, FreeBSD and macOS can be installed on virtual machines running with VirtualBox.