Low-level formatting involves writing to every single sector of the flash memory. Doing this excessively can slightly reduce the lifespan of your USB drive. Use it as a "last resort" fix, not a weekly maintenance task.
Unlike a "Quick Format" that only erases the file system index, a low-level format: Wipes all data: usb lowlevel format
A widely used utility that works with USB drives (via USB-to-SATA/SCSI bridges), providing low-level access to wipe data completely. Low-level formatting involves writing to every single sector
You might need a true low-level (or zero-fill) format for the following scenarios: usb lowlevel format