Virtual Box in Ubuntu

 Virtual Box is a software which you can use to run a Operating System in a virtual environment without installing it on your machine. 

To install it on Linux, it's simple:

Type:

sudo apt install virtualbox

or, you can download it from this link.

If you have downloaded it from the link, go to your Downloads folder or any other folder where you have stored the installation file. There you can install it like any other application.

After installation open the virtual box. You will get to a screen like this (without the virtual machines at the left side):

Then you can click on the new button which is at the top of the screen. You will end up in a screen like this:

Here you can enter the name you want to keep of your virtual machine. You can leave the Machine Folder as it is. Then in the Type option, you can click it and select the type of operating system you want to run. On the Version option, it is the same too. 

After that, you can select the amount of RAM you want your machine to use. The green bar is till where it is okay and the red bar is where you should worry a little. After allocating the RAM, you can click Next button.

Then comes this screen:

Here you can choose to create a virtual hard disk now and click Create. Then:

Here too, you can choose VDI (Virtual Disk Image) and click on Next. Then: 

When you reach here, you get two options, one is the Dynamically allocated and the other one is Fixed size. If you choose Dynamically allocated, your virtual disk will be created but it won't allocate any fix space instead it will fill up the space as you start using the space. In the Fixed size option, the virtual disk will take allocated space from the start. Then: 

Here you can select the storage you want to allocate to your virtual machine. Then: 

Your virtual machine will be created. You can see it at the left side of the screen. I previously had virtual machines created so you can see them there too. Then click on the [Optical Drive] Empty which you can find under the Storage:

After clicking there, click on Choose a disk file.....

After that choose the ISO of the operating system you want to run.

Then click Open. After than you should be able to see the name of you ISO file like this:

After that you can click the Start button which is at the to of the screen:

After that a new window will open and your operating system should be up and running like this:

And there you go! You have your virtual machine running. Have fun with it, test things, mess around with it and a lot. 

Enjoy!!