What is the average lifespan of webpage? Predictably, estimates vary and vary over time. A 1997 special report in Scientific American claimed 44 days. A subsequent 2001 academic study in IEEE Computer suggested 75 days. More recently, in 2003, a Washington Post article indicated that the number was 100 days.

Though presented as a unified experience, a website depends on many interrelated parts: document markup and dynamic code, assorted binary file types, software interpreters and platforms. The challenge of web archive preservation planning is to save this experience, accounting for ongoing changes in the constitutive layers. While web archives and, for that matter, websites themselves haven't been around long enough that we've yet had to contend with issues of wide-scale digital obsolescence at any layer of the stack, we are currently devising strategies to handle such eventualities.

If science reporters, IT industry pundits and digital storage and network infrastructure purveyors are to be believed, devices are being lab-tested even now that can store all of the data in the Library of Congress or transmit it over a network in mere moments. To this list of improbable claims, I'd like to add another: by the most conservative estimates, I transfer more than a Library of Congress' worth of data to the Library of Congress every month.