If you have too many photos, films and songs to store on your computer, or want somewhere to back them all up to, external hard disk can offer extra space without ripping your computer apart. They come in a range of storage sizes, and in a variety of different looks. Some also offer extra functionality, such as wireless compatibility or the ability to share over the internet. A good portable external hard disk is as handy as a pocket on a shirt. You can use one to back up your PC, carry important files with you on the road.