Backing up to a DVD is another cheap option, great for photos and MS Office files such as word and excel, but if you are performing system backups where the volume of data can be quite significant, then this type of back up can become a tiresome chore - as you will have to wait around for data to be written, then removing and reloading fresh DVD's, and you could find you are going through a lot of DVD's each time. Additionally, you may be restricted as to whether you can keep working on your computer, as some software used to run your backups can be temperamental and continuing to use your computer whilst a backup is in progress can often cause backups to fail.
External USB plug and play hard drives are a cheap and easy option; a backup can be a few clicks of the mouse with a simple copy paste. Given these hard drives are compact and can hold large volumes of data, they can easily be stored offsite, which hard drive failure aside, if there is a fire or flood this makes for a very attractive disaster recovery backup option.
Alternatively you can set up and use a free email account for the express purpose to use as online storage. Google's Gmail offers 7 gigabytes of free storage. You can email important files to this account - just watch the size of each email you send, as your internet service provider may have a limit on the size of each email sent. It is easier to send files in small lots, and if you use the subject header as a naming convention for your files, then this will serve you well later should you need to do a search to locate a specific file.
If you are running Microsoft Office a free option is Windows Live Skydrive which offers up to 25GB free online storage.
There are a range of online storage providers that charge a monthly fee, starting from around $5 per month, with options to increase depending upon how much data you want to store. Some providers offer a synchronizing service, so you files can be kept current in real time. Alternatively there are automatic backup providers, which once set up; you no longer need to perform manually. Either of these services is suitable options for large volumes of data, such as database type applications and suitable for a business that is physically spread out geographically, in the event that a disaster should strike head office in one region, then other regions can continue with business without loss or with minimal data disruption to business.
To avoid tears, sentimental loss or worse, regardless of whether you use one or more options - your data backup should be as current as possible. Whilst it is quick and easy to copy data to an internal or external hard drive, consideration should be given to keeping your backups off site, whether this is asking a close friend or relative to keep a few DVD's of your family photos at their house for safe keeping, or managing and storing your data via the Internet in another country.