As a grandparent and writer, I can tell you that nothing would upset me more than to lose years worth of hard work and irreplaceable pictures of my grandchildren that I hold on my computer.

Initial setup and precautions
When you first buy a computer, you want to be cautious of anything that is installed by the retailer. Many times the retailer will install the software using their license and not provide you with a CD. In most cases that will not be a problem, but if your computer happens to crash or the software malfunctions, you don't have anything with which to reinstall it. That doesn't mean you shouldn't buy the computer from that retailer, but you must be cautious and make sure you back up the information on your computer onto either a CD or DVD, or an extra drive (even a thumb drive will often do).

The thumb drive (also sometimes called a pen drive or a flash drive) is a small pen-size drive that fits into your USB port on your computer. They are available customarily in one or two gigabyte sizes, and though most people use them to back up everything but the operating system, if you don't have a CD for your operating system, you might want to make a copy of that as well. They are very inexpensive, usually less than $100 and well worth the price.

If you use CDs or DVDs to back up the information on your computer, make certain you purchase CD-R or DVD-R disks rather than CD-RW or DVD-RW disks so that you don't accidentally write over any of the information on the CD. RW means read/write and R means read-only. As a side-benefit, the read-only disks are often somewhat less expensive than RW disks.

For data files such as Word and Excel, you might want to use read/write disks so that you can add edited copies to the files -- read-only disks don't allow for editing. Once you close a CD-R, you cannot add or delete anything.

In theory, some claim you can't use CD-RW for music files, and CDs made specifically for music are preferred by many people for quality purposes. However, this all depends on the way your music is encoded. If you're just backing up MP3s, Ogg files, or other digital files, you can back them up just like any other file. But if you're trying to create a CD you can play in your car CD-player, then you'll be encoding in the native CD format, and you'll need a read-only platter.