Anyone who reads Giz probably knows that even though your data is "saved," it's still susceptible to the decay of whatever medium is storing it. According to one expert, the problem is nearly unsolvable.
In an interview by David Pogue, Dag Spicer, curator of the Computer History Museum in Silicon Valley, noted that there's no great solution to saving your data other than resaving it again and again. His best advice:
...every five or ten years, you should move it onto a different format, like from VHS tape to DVD. And that's fine, but then DVD is already obsolete, there's Blu-ray, and so what's going to happen in another 10 years?
Making lots of backups is good advice, and on different formats, different places; consider paper as an archival medium...Keeping it on the Web is also not a really great strategy. A very large photo site just went out of business, and they gave people, I think, a month's notice to say, "We've run out of money, get your photos off the site and put them somewhere." Web sites are fine for sharing, but in terms of preserving your data, I wouldn't recommend it.