eli5: What physically happens in a hard drive when data is stored?

Question

eli5: What physically happens in a hard drive when data is stored?

In: Technology

Answer 1

If you put a powerful magnet next to many kinds of metals, that metal becomes a magnet itself.
The hard drive puts a tiny part of the disk next to a tiny magnet, to make that tiny part a magnet.
It then reads and see what parts are magnets.