Technological advances during the past few decades have revolutionized many complex systems that influence human activity. As the rate of technological progress accelerates, these systems will become more complex, and new ones will evolve. Citizens in a technological society need to be able to make intelligent choices about how technology will affect their lives. This requires a better understanding of the technology itself; its potential and its limitations. This is a module for a course designed to introduce students, particularly those not majoring in the sciences or mathematics, to technological concepts. This module explains the conversion of signals (audio, video, etc.) to digital form (a sequence of zeros and ones). The two primary examples are bar codes, which play a growing role in both service and manufacturing industries, and the compact disc (CD, or digital audio). This unit requires no specific background and is appropriate for an introductory course in quantitative methods or technology studies. (CW)