Virtualization is pretty awesome. Maybe you wanna test out some new software without committing to it. Maybe you wanna run Linux and Windows and Mac. You can do a lot of cool stuff with virtual machines.
There are some pretty good paid options out there. Parallels and VMWare offer some solid software that isn’t too difficult to use. But if you consider yourself tech savvy, or maybe kinda tech savvy, and you don’t feel like spending your hard earned bucks on virtualization software, there are some quite good free options out there.
Some of these are free as in they don’t cost anything and some are free as in open source (and also don’t cost anything).
VirtualBox is a really good option. It runs on Linux, Windows, and Mac. It isn’t all open source, but parts of it are. Read more about VirtualBox here.
QEMU is completely open source. Probably best for virtualizing Linux inside of Linux, although it can manage other operating systems. See here for more.
Currently in the process of testing out VirtualBox and QEMU and will report back soon.