HDD (hard disk drive)
Also known as: hard disk drive, hard drive, mechanical hard drive, what is an HDD
An HDD (hard disk drive) stores data on spinning magnetic platters that a moving head reads and writes. It is slower than an SSD but much cheaper per gigabyte, which makes it a popular choice for large external drives and bulk archives.
- Stores data on spinning magnetic platters
- Slower than an SSD but cheaper per gigabyte
- Common for large external and backup drives
How a hard drive works
A hard disk drive records data magnetically on one or more rigid platters that spin at high speed (commonly 5,400 or 7,200 RPM). A tiny arm moves a read/write head across the surface to find and change data. Because that head physically travels to each spot, an HDD is slower than an all-electronic SSD and more sensitive to bumps and drops while running.
The mechanical design is also why hard drives make a faint spinning or clicking sound and use more power than flash storage. They remain common in desktops, network drives, and large external backup drives.
Why hard drives are still used
The big advantage is cost: hard drives offer far more capacity per dollar than SSDs, so they are ideal for storing huge photo and video libraries, backups, and archives where raw speed matters less.
For everyday system drives most people now prefer an SSD, but a hard drive is a sensible, affordable home for media you want to keep but rarely touch — including offloaded files moved off a phone or laptop to free up space.