The following is a Plus Edition-only article written and copyright by Richard W. Eastman."How long will a CD or DVD last?" As you might guess, the only correct answer is, "It all depends."
The one thing to remember about digital data is that there is no signal degradation in the output. In a digital environment, data is stored in "bits," often referred to as "ones and zeroes." Each bit either is there or it isn't. Analog data, however, is stored in an infinite number of signal strengths. This variable information is the problem; if not exactly perfect, the result is degraded audio or images. Analog data will degrade over time; digital data will not.