It is very common to use a bootable USB drive instead of a CD/DVD drive to install the operating system. For Windows there are a ton of software programs that help you create bootable USB drives.
Note: This tutorial assumes you already have the ISO file. If you don’t have the ISO file, you can download it from the developer website. Also, make sure that the USB drive you are using is at least 8 GB and has no important data on it.
Use Rufus to Create Bootable USB Drive
1. First, download Rufus if you haven’t already. Along with a regular installer, Rufus also comes in a portable variant. Download the portable version if you don’t want to install Rufus on your system. In my case I’ve downloaded the portable version. After downloading, install and open Rufus.
2. Plug in the USB drive, and you will instantly see it in the top drop-down menu. Once you see the drive, click on the “Select” button.
3. In the Browse window go to where you’ve stored your ISO file, select it, and click on the “Open” button. In my case, as I wanted to create an Ubuntu bootable USB drive, I selected the Ubuntu ISO. You can choose the ISO of your choice such as CentOS or FreeNAS.
4. (Optional) If you want to, click on the little “Tick” icon next to the “Boot Selection” drop-down menu to compute and see the MD5, SHA1, and SHA256 checksums of the ISO file. This is useful to verify if the ISO file has been tampered with in any way.
5. Select “MBR” from the Partition Scheme drop-down menu and “BIOS or UEFI” from the Target System drop-down menu. If you are trying to use this bootable USB drive on an old system, select the “Add fixes for old BIOSes” checkbox under the “Advanced Drive Properties” section.
6. (Optional) You can change the USB drive name using the “Volume Label” field. Additionally, under “Advanced Format Options” make sure that the “Quick Format” checkbox is selected. As the name implies, Quick Format formats the drive quicker by skipping the check for bad sectors.
7. Click on the “Start” button.
8. Depending on the ISO file, Rufus may prompt you to download additional files. For instance, to create a bootable Ubuntu drive, Rufus prompts you to download the newer version of Syslinux. Just click on the “Yes” button, and Rufus will take care of everything.
9. In the next prompt, select the recommended “Write in ISO image mode” option, and click on the “OK” button. You might also see a drive format warning – click on the “OK” button.
10. As soon as you click on the button, Rufus starts to create the bootable USB drive. Depending on your USB drive, it can take a few minutes to complete the creation process.
11. Once completed, you will not see a completion message but will hear a completion sound, and the progress bar will turn fully green.
That's it! As you can see, it is pretty easy to create a bootable USB drive using Rufus.