A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material.

A computer hard drive (or a hard disk or HDD) is one kind of technology that stores the operating system, applications, and data files such a documents, pictures and music that your computer uses. The rest of the components in your computer work together to show you the applications and files stored on your hard drive. How does a hard drive work?

The hard drive is where a computing device stores data for the long term — not just the things you save, but all the code required for the operating system, the framework browsers use to access the internet, drivers for accessories, and everything else.