Install Ubuntu Linux on Windows 7 or Windows 8 using VirtualBox.

What is VirtualBox?

VirtualBox is a powerful Virtualization software for x86/x64 computers. VirtualBox emulates the features of a computer, and allows you to install any operating system in it. You can install VirtualBox on your PC or laptop, and then you can install any operating system INSIDE it. So you can install and run Windows 7 on Windows 8, Android on Windows 7, ANY Linux distribution on any version of Microsoft Windows. So basically you are running an Operating System inside an application, on your main operating system. This is very useful when you dont want to install other operating system permanently, or you dont want to risk your current OS. Also its very useful for checking out different operating systems. 

I will show you how to use VirtualBox with an example of Ubuntu Linux. Ubuntu is a popular and freely available Linux distribution. You can download the ISO file of Ubuntu here. 

Install or run Ubuntu Linux on Windows 7 using VirtualBox:

-->First download VirtualBox from here. Download the version named "Virtual Box for Windows Hosts" if you are using Windows XP, Windows 7 or Windows 8.

-->Install VirtualBox.
-->Run it, it should look like this:

-->Now, click on the blue icon "New" on the top left corner. Now give a name for the OS you want to install. As I am installing ubuntu as an example, I have written ubuntu as the name. Also select 'Linux' and select the proper OS name from the second drop down menu. If you have more than 4GB of RAM, then only you should choose 64bit operating system.

-->Now click next. Now you need to select the amount of RAM you want for the Operating System you are going to install. Here you are giving a portion of your current RAM to the the new operating system. The new operating system will work with only this amount of RAM which you choose. So choose this correctly. I am having 8GB of RAM in my computer, so I cam giving 1GB(1024 MB) to the new OS. You can give accordingly. 

-->Now you need to create a virtual Hard Drive for the new operating system. Your new operating system will work on your current hard disk, but you will make a file on your current hard disk, and that file will work as the hard disk of the new operating system. Your new operating system wont see anything outside that file. Select "Create a virtual hard drive now", and click create.

-->Now the first option is automatically selected. Dont change it unless you wish to use your new OS with a different software. Click next.

-->Select "Dynamically Allocated", click next.
-->Now you need to decide where your new Operating System will be stored on your existing hard disk. Choose a location where you have much empty space, by clicking on the yellow folder icon. You can leave this option unchanged if you have enough free space on your C: drive. Now select the maximum file size. This will the maximum amount of hard disk for the new Operating System you are creating. 8-10 Gb is enough for most purposes, but if you plan heavy usage on the virtual Operating System, then you can increase it to your choice. Click on create.

-->Ok, so now you have all the settings and parameters for the new Operating System. Your new operating system will now be showed on the main screen of VirtualBox.
-->Before starting the new Operating System, you need to install it. Now there are two options (1) You can burn the downloaded ISO file to a CD/DVD and insert that CD/DVD to your CD drive. (2) You can emulate the ISO file in an emulation software without using a CD. You can download DAEMON TOOLS from here. Then you can just mount or emulate that ISO file in DAEMON TOOLS. DAEMON TOOLS will create a virtual or "duplicate" CD drive in your computer, and you will use that drive for installing the operating system.
-->So now, lets install the operating system. Click on the green colored "Start" button.
-->Now, select the drive in which your CD/DVD is present. If you are not sure which drive it is, just go to Computer and see it. Press start.

-->Thats it! You now have your ubuntu running inside your Windows 7/8/XP. You can now use ubuntu whenever you want. You will need to install it inside the virtual machine of virtual box, if you want to use all its features.

-->This way, you can install and use any operating system inside any Operating System.

Feel free to ask any questions in the comments box below!