After you download any Linux distro from the internet, you have to burn it to a DVD, CD or a number of CDs to install it. That CD or DVD is generally used only once after which it lies unused , and worse, almost every Linux distro comes up with a new release every 6 months. So if you are in the habit of upgrading to every new version, you must have dozens of CDs lying at the bottom of your drawer. What a wastage of CDs! But with a little trick you can install any Linux directly from the hard disk without burning a single CD or DVD. The prerequisite of this trick is to have an operating system already installed on your computer. This is obvious because unless you are able to boot into your machine, you can't install anything; and we are not going to boot from the Linux disk because we aren't burning any. Here I'm going to focus on Microsoft Windows as the pre installed operating system.