Take Linux and Run With It
"How do you run an operating system?" may seem like a simple question, since most of us are accustomed to turning on our computers and seeing our system spin up. However, this common model is only one way of running an operating system. As one of Linux's greatest strengths is versatility, Linux offers the most methods and environments for running it.
To unleash the full power of Linux, and maybe even find a use for it you hadn't thought of, consider some less conventional ways of running it -- specifically, ones that don't even require installation on a computer's hard drive.
We'll Do It Live!
Live-booting is a surprisingly useful and popular way to get the full Linux experience on the fly. While hard drives are where OSes reside most of the time, they actually can be installed to most major storage media, including CDs, DVDs and USB flash drives.
Read more at LinuxInsider