#BootableUSB
Bootable USB - A bootable USB is one that contains instructions for your computer's bootloader to load up various assets to run an operating system.
Normally, bootable USBs are used for operating system installers, so your system will know to boot into the installer, and the installer will essentially unpack a large compressed file containing the actual operating system's resources. If you install any operating system onto another USB drive, then it will also be considered a bootable USB, but for an entire operating system this time.
Rufus https://bit.ly/2EHGBlJ
Kali Linux Live 64 https://bit.ly/34N8ROA