What are Operating Systems?

An operating system is the main software installed on a computer that controls the hardware and lets applications run by allocating resources, including memory, CPU, input/output devices and file storage.

It manages memory, processing, storage, and devices so users can actually do anything with the machine.

Source: YouTube - Operating Systems: Crash Course Computer Science (CrashCourse)

What is a Virtual Machine?

A virtual machine is a software-based computer that runs inside another computer. It acts like a real system with its own operating system, storage, and memory, even though it is only using the host machine’s hardware.

It's cheaper and you get to test out OS before installing them for real (if you plan to). Check out this bearded guy's great vid about it!

Source: YouTube - you need to learn Virtual Machines RIGHT NOW!! (NetworkChuck)

What is VirtualBox?

VirtualBox is a virtualization software program by Oracle that lets you create and run virtual machines on your computer.

It's open-source and allows you to run multiple operating systems on a single device at the same time. There's a ton of tutorials out there. Just search your chosen OS with "Virtualbox" beside it.

Source: YouTube - How to use VirtualBox (Kevin Stratvert)