For a complete look at these commands, you should look them up in the DOS Help System. Format Formatting a disk prepares it to receive data. An unformatted disk cannot be used until it has been formatted. Part of this formatting process is installing a file system. For DOS disks, that is FAT-12.
Disks come in various sizes and densities.
You could bend them, though they probably would not work afterwards. These first DOS disks could be formatted to hold 160K of data on one side of the disk. But inside this plastic shell there is a thin, and very floppy, mylar disk. BTW, for trivia buffs, Toshiba introduced a 2.88MB floppy drive in the late 1980s, but it never caught on. Note that you cannot format a hard drive if you have booted into it.