The disks inside our computers get bigger every hardware generation. They are keeping pace with the amount of data we have to store, or vice versa. It it hard to tell which is the chicken and which is the egg. Now that we all have digital cameras with large megapixel ratings, for example, we need more room to store our photos. What once was stored in a shoebox in the closet is now stored on our computers. Most of us also have word processing data, spreadsheet data, emails data, incoming email attachments, and a million other files that take up space.
Even if we do not want or need to remove those files from our main hard disk, we still need someplace to back up all of that information. For purely archival purposes, many of us save information to DVDs. This is an excellent practice for old files that we may never need to access again, but want to save just in case. It is not very workable for files that we really may need at any time, and that is a lot of files these days. You never know when you may need that one perfect photo from your cousin Virgil’s wedding.
And, of course, backing up your entire computer onto DVDs is a task fraught with worry and the consumption of a lot of time and effort. DVD drives are slower than hard disks, by far, and more prone to small errors that can cause big problems. Sometimes the only answer is an extra hard drive. That used to be a very expensive proposition, but the prices of external drives have fallen quickly in the last few years, and they are now easy to connect to our computers and offer high speed, reliability, and high capacities. You can now buy a drive that will hold a full terabyte of data (about 1,000,000,000,000 bytes) for under $100. Drives larger than that are readily available. Better yet, they interface to your computer through a USB port. Nothing could be easier.
Most of these drives need to be plugged into an electrical socket (or a surge protector) as well as into the computer. This is the sort of drive that most of us need. As a rule of thumb, buy all the drive you can afford, easy since they are no longer very expensive. Remember that you can use one drive for more than one computer if you want to, though it is easier to have one external drive per computer. Buy a drive large enough to back up your computer(s) three times, so that you always have at least two older backups while you are performing a current one.
It is also possible to buy a USB hard drive that does not require a connection for external power. Instead, these use the power available from your USB port. These are more problematic than drives that plug into the wall. Not all USB ports are properly engineered, and may cause problems by not supplying the drive with enough power. This causes problems with writing data, which is even worse than using DVD. Generally, these USB-powered drives are also slower. I will admit to owning one, but I just use it like a very large thumb drive because it is both small and very portable.
In short, you need storage space in order to back up your computer, and to offload files from that computer so they are not taking up room there. You would do well to buy a high-capacity USB external hard drive for these purposes. Unless you need extreme portability, buy a drive with its own power supply. Buy it from a manufacturer you trust, such as Western Digital, Maxtor, Samsung, or Seagate. There is a wide selection available at many online suppliers, such as Newegg. Look around at reviews of the drives you are interested in. A little research will take you a long way.