You may think that those photos on Facebook or all your tweets may last forever, or might even come back to haunt you, depending on what you have out there. But, in reality, much of our digital information is at risk of disappearing in the future.
Unlike in previous decades, no physical record exists these days for much of the digital material we own. Your old CDs, for example, will not last more than a couple of decades. This worries archivists and archaeologists and presents a knotty technological challenge.