An external hard drive is an excellent way to back up files on a computer, or to add more space to a computer. It is easy to use even for people who are not familiar with computer hardware, because it generally just connects to the computer through a USB port and is ready to use without any hardware or software installation necessary. To choose the best external drive, consider how much extra space you want, if it needs to be portable or not, and what brands have the best reputations.
External hard drives are available in at least the same capacities as the regular hard drives inside a computer, and some can hold a huge amount of information. As technology improves, the size of available drives increases as well. Though price does go up depending on the capacity of the drive, in general, it is best to buy one that is larger than you will expect to need, in order to get more life out of the hard drive.
In addition to the size capacity of the hard drive, consider whether you want a stationary hard drive or a portable hard drive. Though all are relatively portable, some are designed to be moved more easily. A true portable external hard drive will typically not have a separate power supply, but will instead be powered through the USB port on the computer. You would generally not leave a portable hard drive connected all the time.
On the other hand, a stationary external hard drive will generally include a power supply and will plug into a power outlet as well as the computer. As a general rule, a portable drive will be slightly more expensive for a smaller capacity, simply for its smaller size and greater portability. This type of hard drive will also generally spin at a slower speeds, making it somewhat more durable and less susceptible to damage from bumps. A stationary external drive will be slightly larger, both in physical size and capacity, and somewhat less expensive; however, it may be somewhat more susceptible to damage and corruption if it is knocked over.
Brand is another consideration when choosing an external hard drive. Some people have certain brands they prefer, but in many cases it is just a matter of personal preference. It may be helpful to read reviews online of particular hard drives to see if other customers are happy with them, as well as if they hold up over time without failing. Extended warranties are sometimes available as well.