A hard drive is a type of storage device. The main storage device in most personal computers is a hard drive, which may be why some people don’t know what they are, because they don’t see them. They are what store all your files (pictures, music, videos, documents, etcetera) and your operating system. This will probably be the case for a while until flash storage takes over. Hard drives, unlike flash storage, do have moving parts, which means they are prone to mechanical failure. A hard drive can and will fail (probably after a few years), so do your backups. Even if you get a new computer or hard drive before your current one goes kaput, beware the possibility of failure.
This is a 3.5″ SATA hard drive.
Photo by Asim18. Used under the Creative Commons Attribution 3.0 license.
This is the inside of a hard drive. It’s remotely like a record player on a much smaller scale, as you might be able to see.
Photo by Alessio Sbarbaro. Used under the Creative Commons Attribution 3.0 license.