Hard disk facts for kids
A hard disk drive (HDD), also called a hard disk or hard drive, is a very important part of a computer. It's like the computer's long-term memory. It stores all your information, like games, photos, videos, and documents, even when the computer is turned off.
Hard disks work by using magnets. They store data on spinning metal or glass discs called platters. A special arm with a tiny head reads and writes information onto these platters, much like how an old record player works.
The amount of information a hard drive can store is called its capacity. This is usually measured in gigabytes (GB) or terabytes (TB).
- A gigabyte is about one billion bytes.
- A terabyte is even bigger, about one thousand gigabytes!
Older hard drives used to store much less, often measured in megabytes (MB), which is a million bytes.
How Hard Drives Connect to Computers
Over time, many different ways have been created to connect hard drives to computers. These connections are called "interfaces." Even though the way they store data (on spinning platters) is similar, the interfaces change how fast data moves and how they connect.
Today, the most common way to connect a hard drive is using something called Serial ATA, often shortened to SATA. Before SATA, a common connection was called "IDE," which is now known as Parallel ATA.
For very large computer systems, like those used in big data centers, other types of connections are used. One popular one is called Fibre Channel. Another important interface, especially for powerful computers called servers, is SCSI (pronounced 'scuzzy'). There are different versions of SCSI, each offering faster speeds and higher prices.
Sometimes, in servers, many SCSI hard drives are used together. This setup is called RAID. It helps protect important data from being lost or damaged, making sure information is always safe.
Related pages
Images for kids
-
Inside a 2.5-inch hard disk, often found in laptops.
-
A hard disk from 1997, taken apart and labeled.
-
A broken hard disk showing its glass platter.
-
A close-up view of tiny magnetic spots (bits) on a hard disk platter.
-
A hard disk with its discs and motor removed, showing the parts inside.
-
The head stack, which holds the read/write heads.
-
A close-up of a single read-write head.
-
How much data hard drives could store over the years, compared to Moore's law.
-
Two Seagate Barracuda drives from 2003 and 2009.
-
Different sizes of hard drives, from 8-inch to 1-inch.
-
A smaller 2.5-inch hard drive next to a much older, larger 5.25-inch one.
-
The inside of a 1998 Seagate hard disk.
-
A smaller 2.5-inch SATA drive on top of a larger 3.5-inch SATA drive, showing their connectors.
-
A close-up of a hard disk head resting on a platter.
-
Two 2.5-inch external USB hard drives.
