What does a hardrive store data on?
The harddrive stores data on a single magnetic disk, somewhat
compareable to a CD in the way that it spins, its round, and it
stores data. The "head" of the harddrive uses magnetic fields to
excite different areas of the disk to store a binary code such as
"00100010." Millions upon billions of these codes are stored on the
disk with each code being a single command.