All of we know about portable software that can be run without installing. So we don't have to make changes to the computer. But amazing thing is that operating system also can be portable. Best portable operating system in this world is linux. There are many linux distros such as Ubuntu, BackTrack, RedHat, Fadora etc. All can be run directly from USB pendrive.
So I have made a full tutorial about making portable Linux on removable device on "How to Run Linux from USB". Enjoy it.
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