"Hard drive" is a common term used in the computer world for the component in computers and electronics that provides long-term storage of information.
The Hard Drive as Storage
As you use your computer, you create documents and other bits of information to be stored. The saves these items, alongside the software and files that allow you to easily use and interact with your computer, including the operating system.
When you open an application or document, your computer accesses it from the hard drive. Larger files or programs can take longer to access because the computer needs to retrieve the information from the hard drive before presenting it to you in a useable way.
Measuring Hard Drive Storage
Hard drives come in a variety of storage sizes. As of publication, hard drives are typically measured in gigabytes and terabytes , which are units of measurement for a hard drive's storage capacity.
For example, 500GB hard drives are common in many modern computers. The average four-minute song on iTunes is approximately 4MB in size. There are 1,000 megabytes in 1 gigabyte. This means that a computer with a 500GB hard drive could store 250,000 songs.
Standard Hard Disk Drive
A hard disk drive consists of circular metal disc-shaped platters which store the computer's data. An actuator arm runs between the platters, reading data off the hard drive. These platters constantly spin while the computer is on, almost like a vinyl record player. HDDs are the most common and inexpensive form of hard drive.
Solid State Drive
Unlike a hard disk drive, a solid state drive has no moving parts and the data is stored on flash memory chips instead of metallic platters. SSD technology is faster than HDD and less prone to failure since there are no moving parts. Since SSDs are newer technology, they cost more per unit of storage than an HDD.