Almost all computer users need to preserve data occasionally, and probably the most common method is to write the information onto CD or DVD data disks. For most computer users, preserving data for a year or two is sufficient. In fact, many people are only concerned with preserving data until next year's tax season. However, genealogists, historians, archivists, and a few others are concerned with much longer preservation. We often think in terms of decades or even centuries.
Patrick McFarland has written an in-depth article that describes CD and DVD recordable media, explaining the various formats and their strengths and weaknesses. He points out that most of today's "record-at-home" CD and DVD disks will only last a few years. However, certain brands are expected to be useable for at least 70 years, and one manufacturer's products may last for up to 100 years.
McFarland explains the differences between "pressed" CDs (made by the thousands in a factory) versus "burnt" CDs (recorded one at a time on a computer). He then focuses mostly on CD and DVD disks recorded (burnt) on computers. His article describes the advantages and shortcomings of the different blank disks that you can buy in a local computer store, online, or by mail order. He also tells why DVD+R disks are much better than DVD-R.
The article ends with McFarland's recommendation for the best archival quality writeable CD and DVD disks. He even tells which brand he buys for his own archival storage.
I think that one part of McFarland's article should be required reading for all:
Unlike pressed CDs/DVDs, 'burnt' CDs/DVDs can eventually 'fade,' due to five things that affect the quality of CD media: sealing method, reflective layer, organic dye makeup, where it was manufactured, and your storage practices (please keep all media out of direct sunlight, in a nice cool dry dark place, in acid-free plastic containers; this will triple the lifetime of any media).
The article is liberally spiced with technical terminology, but most anyone can understand his plain English recommendations, given at the end. You can read this excellent article on Patrick McFarland's blog at: http://tinyurl.com/ycowgr
After reading McFarland's article, I ordered 100 archival-quality CD disks for my own use. How long do you want your information to last?