Not just for spies: The PC on a memory stick that doesn't leave a trace of your browsing history or documents

If you are either super important, super paranoid, or a super spy, there are times when you need to be able to use a computer and not leave a trace.

Now, a clever piece of software lets you carry your own personal PC which you can carry inside your pocket - and once you have finished using it, no-one will ever know.

Technically, what you are carrying is not a whole computer - instead it is a simple USB memory stick.

But within it is a full operating system (like Windows), and when you plug it into a PC, that computer will restart into your own personal set-up, called Tails.

When you have finished, shut down the computer, put the USB stick back in your pocket, and the PC will never know it has been used.          Read More