Answer:
A bootable flash drive will allow you to boot the computer from the file system on the flash drive rather than your hard drive. Your computer has a boot sector on the hard drive that contains information about its use.
Formatting a flash drive is the best way to prepare the USB drive for use by a computer. It creates a filing system that organizes your data while freeing more space to allow for additional storage. This ultimately optimizes the performance of your flash drive.