What is an External Hard Drive?

An external hard drive is the same type of hard drive as you would find inside a PC or laptop, except that it is mounted in a separate enclosure. It can be used to store information (data) permanently or temporarily, in the same way as a computer's hard drive.

External hard drives (the actual drive itself) come in two main sizes (physical size), 2.5" and 3.5". The 2.5" drives are the same as you would find in a laptop computer, whereas the 3.5" drives are identical to hard drives found in desktop PCs. The difference is in the interface that connects the external hard drive to your computer. Usually external hard drives connect to the computer via a USB/Firewire cable, most modern operating systems will automatically recognise the hard drive as a storage device, and assign it a drive letter. The fact that external hard drives are simply placed in an enclosure, means you can usually change the actual hard drive itself without too much effort. This allows you to swap drives between enclosures, so you only have to buy one enclosure for many drives (of the same type).