Virtualization is quickly becoming an important tool for the IT industry. It's already being used for many purposes, from testing software to running virtual servers. What is virtualization? The concept can be mind-boggling at first because most people aren't used to it, but it's easy to grasp. Virtualization is equivalent to running one to multiple computers inside of another. Your physical computer is called the host, and you can have multiple virtual computers being run inside the host.

What does this mean? Well, here are a couple of examples. If you're a Mac OS user who has ever felt the need to run Windows software, you could download some virtualization software onto your Mac and create a virtual machine. Then you would install Windows (you need a seperate license) onto the virtual machine, then presto! You can run Windows without ever leaving Mac OS.

Similarly, if you're running Windows and you want to see what this Linux business is all about, you go through the same procedure. Download the virtualization software, create a virtual machine, run Linux on said virtual machine. Now you can try Linux from the comfort of your familiar Windows OS.

Of course these examples aren't all you can do. Feel free to mix and match!

Virtualization has its pros and cons:

Pros:
-Pretty easy to set up, and you can do it for free. So you can get started quick!
-You can easily create many virtual machines with any OS of your choice
-No dual booting! All the hard drive information for your virtual machine is typically stored in a file! This file can also automatically expand to accommodate more data. Easy!
-Display, sound, networking, drives, and USB are all supported.
-You can wreak havoc on your virtual machine without ever hurting your host PC, since the virtual machine is in its own little bubble. Just make sure to close off the networking if you're infecting it with bad stuff.
-There are things that virtual machines can do that are difficult to accomplish on a real PC, keep your eye out for features that could make your life easier. Mounting floppy and CD images is an example.

Cons:
-Virtual machines can be slow... BUT in newer processors there is virtualization support that makes virtual machines perform closer to the full speed of the host. Check your specs, you may be pleasantly surprised, especially if you have a Core 2 or an equivalent AMD.
-Resource hog! Remember, you ARE running multiple computers at once. Make sure you've got enough memory and hard drive space to throw around.
-Can be buggy sometimes. The technology's new, give it time.
-3D gaming may not work correctly, if at all. Keep it simple.
-You may need additional licenses for software just like if you were installing it on another physical computer. Read the fine print if you're staying legal.

And finally, FREE STUFF!
VirtualBox - This one's my favorite since it's easy to set up AND is multiplatform. Has some nifty features depending on whether you grab the binary or the open source. Up to you. It was recently acquired by Sun too, fun fact.
VMware Sever - I had a helluva time setting this one up (in Linux), but it works in the end. VMware tends to be recognized more widely than VirtualBox. You may have to register (free, fill out a form) to get this one.
Microsoft Virtual PC - I know this is a shocker, but this is Windows-only. What really surprises me is that this is free as well. I used it back before it was bought by Microsoft, and it got the job done.

Whether it be VirtualBox, VMware, or Virtual PC, they all have similar functionality. You can create and run multiple virtual machines at a time. So there's something you can do if you have a use for it, or if you're just bored.