^Link^
Quoted from their user manual:
"Sun VirtualBox is a collection of powerful virtual machine tools, targeting desktop computers, enterprise servers and embedded systems. With VirtualBox, you can virtualize 32-bit and 64-bit operating systems on machines with Intel and AMD processors, either by using hardware virtualization features provided by these processors or even entirely in software, at your option."If you didn't understand that somehow, it basically runs a computer in your computer.
I'm installing it now after seeing it at my friend's house. I don't care if you've heard of it a million times, or if it's insanely old.
Discuss.