How Data Dies (and How It Can Be Saved), Gizmodo

"What we're talking about is digital rot--or data rot or bit decay or whatever you'd like to call it--systemic processes which can mean death to data. Kind of a problem when you'd like to keep it around forever. Let's paint this in broad strokes: You can roughly break the major kinds of rot into hardware, software and network. That is, the hardware that breaks down, the formats that go extinct, and the online stuff that vanishes one way or another."