Linux environments work just like a typical operating system but run entirely from a CD or USB stick — the latter being the most common choice these days. Since nothing is written to the host computer’s local storage, when you’re done all you need to do is remove the media, reboot, and everything will be exactly as it was. There are a number of uses to this, from simply test driving Linux to troubleshooting a Windows PC, or work on the go from someone else’s computer but running your own OS securely with all your personal files and settings.