Operating System that can be installed in a USB

Running an application from a USB drive is common. But do you know you can install and run an entire Orating System in a USB drive. There are some Linux distributions which can be installed and run in a USB flash drive.
It is a convenient option if some day, you stucked into error screen because of your default Operating System failure & you urgently need to copy some files from your system or you don’t have access to a computer’s operating system(password protected) & you want to copy files from it.

Here is the list of some well-known Linux distributions that can entirely run from a USB flash drive:

• Ubuntu – Based on Debian
• Google Chromium OS - OS from Google
• SLAX – Based on Slackware
• Knoppix – Based on Debian
• Gentoo – Based on FreeBSD
• Kubuntu – KDE Ubuntu version
• Xubuntu – Light Ubuntu version uses Xfce desktop environment
• gOS – Based on Ubuntu with an Enlightenment interface
• Damn Small Linux – Debian (Knoppix remaster)
• Puppy Linux – Barry Kauler wrote almost everything from scratch
• UBCD (Ultimate Boot CD) – Diagnostics CD
• SuSe Live DVD – Based on the Jurix distribution
• System Rescue CD – Linux system on a bootable CD-ROM for repairing your system and your data after a crash
• Feather Linux – Knoppix remaster (based on Debian)
• FreeBSD – derived from BSD
• Mandriva One – formerly known as Mandrake Linux
• Fedora – Another community driven Linux distribution
• Linux Mint – Elegant Remix Based on Ubuntu
• MoonOS – Based on Ubuntu

Choose Linux distro as per your requirement. If you are looking for smallest operating system then it’s Damn Small Linux of 50.6 MB only, needs  16MB of Ram to run.