My favorite external hard drive is the My Passport Ultra.
It has 1 terabyte of memory and, via a USB cable, it hooks into your computer so that your computer’s backup system automatically backs up your entire computer to the hard drive as often as you have chosen to have it back up.
I love the My Passport Ultra external hard drive because I just hook it up and leave it! I don’t have to worry about anything being lost in case of a hard drive failure or even an accidental delete of a file, because I can easily access what I need by restoring it from my external hard drive. Plus, there is extra room for me to add extra backed up files of photos or other files I want to be extra-sure I wont lose.