Before the IDE interface was introduced in the mid 1980s, a hard drive and its controller were separate and oftentimes proprietary. For early computer users, this caused a great deal of frustration. A controller from one manufacturer, for example, wouldn't work with a hard drive from another. What IDE did was combine the hard drive and controller into a single unit and standardize the connection of hard drives to computers.

The IDE interface has since evolved into the standard method for connecting floppy drives and CD and DVD-ROMs in addition to hard drives. Each of these devices is connected directly to a motherboard via the host adapter. The controller for the device is integrated into the device itself, whether it's a hard drive, floppy drive, or an optical drive (hence the term IDE, or Integrated Drive Electronics).

Most motherboards feature two IDE interfaces, allowing users to connect up to four IDE devices to their computers. Many people don't realize this, utilizing only a single hard drive, an optical drive, and oftentimes a floppy drive as well. This extra IDE connection could be used to connect an additional IDE hard drive to a computer, providing a user with more disk space for storing files.

On eBay, you will find a wide range of auctions for IDE hard drives both new and used. When shopping for such a device, ensure you're purchasing one that's powerful enough for your applications. If you plan to run demanding audio and video software, a faster 7,200 RPM drive is often beneficial. If you're simply looking for an additional drive for storing files, a typical 5,400 RPM drive is more than sufficient for loading small files and programs.