There are a lot of options now available to both personal and business computer users.
Using a USB pen is probably the cheapest and easiest data back-up solution ideal especially if you don’t have very much data you wish to protect against loss.
Now you can buy massive hard drives such as the a one terabyte USB drive. But hard drives are vulnerable to virus attack or hardware failure so you might want to consider additional back-up of critically important data to a CD Rom if it is very valuable to you or irreplaceable.
Back it up to an independent server is another possible solution but don’t forget that a server elsewhere might fail.