Bootable USB drives are most commonly used for installing an operating system, especially for Live Linux distributions, whose Live USB drives let you run and install the operating system. There are also certain system utilities that use the Live CD/USB system. Whether you're looking to create a bootable USB drive for installing a new operating system, or just want to have it around in case you need a bootable system for computer repair, creating a bootable USB drive is as simple as downloading the ISO you need and the right software for creating your drive.
Download the Universal USB Installer, a Windows-only utility for creating a bootable USB drive using a downloaded ISO file. Universal USB Creator can create a bootable USB for dozens of different Linux distributions, as well as the installers for Windows Vista and Windows 7, and even the utilities GParted and System Rescue CD (see Resources).
Download the ISO file for the operating system or utility of your choice. If you're replacing your Windows operating system with Linux, you may want to test a few different Live USB systems before committing to one installation. If you just want a bootable drive to access a broken file system, "PC World" magazine recommends using Puppy Linux.
Plug your USB drive into the computer. Make sure that the USB drive has at least 1 GB of free space. Open "My Computer" and make note of what letter Windows has designated for the drive. The letter designation is located beside the name of the device. If you have any files on the USB drive, copy these to your hard drive to prevent any accidental file loss.
Open the Universal USB Installer and select your Linux distribution of choice from the drop-down menu at the top of the window.
Click the "Browse" button beside "Step 2" and select the downloaded ISO file from where you saved it on your computer. Make sure that the ISO file and your selected distribution go together.
Choose the letter designation for the USB drive that you want make bootable. If you want to erase the current contents of the drive, select the "Format" checkbox beside the drive letter drop-down menu.
Designate any additional space on the drive for saving files or changes you make while running the Live system. This is not necessary to make the bootable USB.
If you want to create a USB drive to create a multiboot environment -- one that gives you the option to boot up one of multiple operating systems and utilities -- you can use YUMI, or Your Universal Multiboot Installer. Note that you will need more space on your USB drive if you choose to multiboot.
Formatting the USB drive erases everything on the USB drive.