Archiving involves storing digital assets in a way that allows safe and permanent access to them many years down the road. By definition, an archive will protect your data from most types of damage, including fire, water, earthquake, and electrical/static charge.
Be aware that an archive is different than a backup. An archive preserves important data on a more permanent basis, whereas a backup provides quick access in the event of failure of your primary storage device or any other problem that renders the original file unusable. In the digital photography world, archiving refers to storing data in a way that is robust, safe, and protected. Today, this means copying your most important images to DVD, Blu-ray disc, or some other form of write-once media. However, as with all technologies, CDs, DVDs, and Blue-ray will at some point become obsolete, so you will need to remember to migrate your data to newer generations of permanent storage before the older generation becomes completely inaccessible.
Mike Hagen, Thousands of Images, Now What?, 2012, p6.
Archiving is not the same as backup. According to the above definition, I am not archiving the majority of my photos. I am, however, backing them up when I transfer a copy to an external hard disk or to an online storage site. The only thing I archive is my photo books and I am all right with this. My most important photos are in photo books, along with information about the photos, and whenever I create a photo book, I save the PDF onto DVD.
Are you archiving or are you just creating a backup?
All About Images Blog 
I think there is some semantics going on here as well. Archiving digital information is by definition an ongoing en devour due to the constant changes in technology. Optical disks are write once, but they are a dying technology that computers are leaving behind in this streaming, online world. Even CDs, DVDs, and Blue-Ray Disks have fairly short lifespans before degradation starts setting in. Manufacturers will tell you 100 years, but the Library of Congress says only 5 to 10 years before you should redo the archive on new media. You need to check those “Archives” at least every three years to make sure they are still good and fully readable. This advice was take from a book published in 2012. Two years is a lifetime in the computer / technology world. I keep 4 copies of all my photos; on my computer, on an external hard drive, on the cloud, and as prints (mostly in a photo books). The print is still the longest lasting, archival storage for your digital images!
Thank you. Very helpful.
I would seriously reconsider using DVDs for long-term archiving. According to a document on the U.S. National Archives website (http://www.archives.gov/records-mgmt/initiatives/
temp-opmedia-faq.html) says, “CD/DVD experiential life expectancy is 2 to 5 years even though published life expectancies are often cited as 10 years, 25 years, or longer. However, a variety of factors…may result in a much shorter life span for CDs/DVDs.”
Pre-recorded CDs and DVDs will generally last many years, but the difference between pre-recorded music and video CDs and DVDs that you buy in the store and writable CDs and DVDs is that the pre-recorded discs are pressed, while the writable discs are burned.
Patrick H. Corrigan
Author, Data Protection for Photographers (http://rockynook.com/book/0/259/data-protection-for-photographers.html)