What is virtualization?

You have probably thought at some point: “I would like to try another operating system, but I do not want to mess up my computer.” Well, virtualization is exactly the answer to that fear. It means creating, inside your physical computer, other «virtual» computers: machines you can see on your screen and that work like a real computer, but that are really just programs managed by yours.

Imagine a dollhouse inside your big house. It has its own rooms, you can furnish it as you like, move it around and even «break» a wall to test things… all without the big house suffering at all. That is virtualization: your own space to experiment freely and without risks.

And what role does VirtualBox play?

VirtualBox is the tool that makes that idea real in the simplest way possible. It is a free and open-source program: you can use it without paying anything, and it is even designed so anyone can study and improve it. It is developed by Oracle, a major software company, and it works on all the usual systems: Windows, Linux and macOS.

In this course you will learn to install it, to create your first virtual machines and to set them up so they run perfectly. It does not matter if you have never touched this world: we will go step by step, in plain language.

Two words you need to know: host and guest

Before moving on, get familiar with two concepts, because you will see them in every chapter. The first is the host, which means «host/anfitrión»: it is your real computer, the one that lends its resources (memory, processor, disk) so virtual machines can exist. The second is the guest: the operating system that runs inside a VirtualBox window, like an invitee staying at the host's house.

What is it for? Common use cases

VirtualBox has as many uses as you can imagine, but almost all of them fit into one of the cases below. Read them calmly: they will help you understand why it is worth learning to use it.

• Test without fear: install and «break» systems by trial and error without damaging anything on your machine.
• Run old programs: if an application no longer works on your current system, give it a virtual machine with an older system where it still works.
• Learn: it is the perfect way to get to know Linux, old Windows versions or other systems without risking your installation.
• Test software safely: unknown software gets installed in an isolated environment, far from your files.
• Set up servers or test environments: to study, practice or work without touching your main computer.

As you can see, the common thread is safety: what happens inside a virtual machine stays inside it.

Scheme: a computer inside another

The big advantage

Let us sum it up in one sentence: you can make mistakes without consequences. If you install something wrong inside a virtual machine, a program breaks or the whole system disappears, none of that affects your real computer. It stays intact, as if nothing happened. That freedom to experiment is what makes virtualization so valuable.

In the next chapters you will learn about the types of hypervisors, install VirtualBox on Windows and Linux, and create and configure your first virtual machines. Let us go!