If you want to experiment with different operating systems, like Linux Mint, Tails or even Windows 10, or just have a secure OS in your pocket that won't leave traces on public computers, you'll want to know how to create a bootable USB drive.
With a bootable USB drive, you can override a PC's native operating system, basically running your own desktop environment on a flash drive. You probably have a thumb drive lying around, and converting it to a bootable USB drive is fairly straightforward, as long as you have the disk image, or ISO file, of the operating system you want to install on it.
The program you'll need is called Rufus, and it's completely free. It also works with a multitude of operating systems (excluding Mac's OS X).