An Introduction to Digital Media Book by Tony Feldman; Routledge, 1997 part 4

To contrast analogue and digital information further, we can return to our wristwatch parallel. You can always tell when people are using a digital watch. Ask them the time and they will invariably say something like, 'It's 4.41'. How often do you really need to know the time to the exact minute? An analogue watch user will just glance at the timepiece and say, 'It's about a quarter to five'. In digital timekeeping it is always one time or another. It is never 'about' anything. However, there is an instant when a digital watch is speechless. When the display flashes from one second to the next there is a tiny gap in the information. So, although the watch seems to supply a constant and exact reading of time, it is in fact a discontinuous display sampling individual moments of time and displaying them.It is worth noting that although today we take for granted that computers are entirely digital, it was not always so. The earliest electronic computers were actually based on the measurement of analogue quantities. For example, an analogue computer would do its sums by passing an electrical current of a known value across a wire which would put up a known amount of resistance to the passage of the current. Because a basic law of physics tells us that voltage is always the result of multiplying the size of a current by the resistance of its carrier, we can effectively perform a simple multiplication just measuring the voltage across the wire in the computer. This simple idea of measuring related analogue quantities was the basis of analogue computing and it worked. But it worked slowly and laboriously. Digital computers are vastly more efficient. They work by just measuring whether electronic switches or 'gates' inside them are either open or closed. The condition of either being 'open' or 'closed' creates the two distinct states needed for binary code language. Adding up numbers in this way-which is all computers really do-is dramatically faster than stitching together calculations by trying to measure currents, resistances and voltages thousands of times every second. Indeed, today's most powerful machines can process millions of instructions every second to carry out the behest of their programmers. In other words, digital computers are not merely fast. They are faster than we can possibly imagine.So-although it was not always true-today when we go digital, we are speaking the exclusive language of computers.

SPEAKING THE LANGUAGE OF COMPUTERS Why is the distinction between analogue and digital information so important in digital media technology? The answer lies in what you can do easily with digital information that you cannot readily do with its analogue counterpart. In other words, the digital revolution is founded on the distinctive characteristics of digital information that set it apart from the real world of analogue experience. The unique features of digital information are the key to its commercialisation and, ultimately, to its potential impact on our lives. What, then, is uniquely special about digital information? There are five key factors.
. Digital information is manipulable
. Digital information is networkable
. Digital information is dense
. Digital information is compressible
. Digital information is impartial

DlGITAL INFORMATION IS MANIPULABLE By taking information out of the analogue world-the 'real' world, comprehensible and palpable to human beings-and translating it into the digital world, we make it infinitely changeable. In the analogue world, the reshaping of a page of information or a physical object requires some exercise of brute force. Usually, however careful we are, the change inflicted causes damage. The process is difficult, slow and untidy. More important, if we take something apart in the real world it is often difficult, if not impossible, to put it back together again. If we translate analogue information into a digital form, however, we translate it into a medium which is infinitely and easily manipulable. We are able at a stroke to reshape the information freely-whatever it represents in the real world-in almost any way we wish and we can do it quickly, simply and perfectly. Then, when we are ready, we can reconstitute and display it as new information which human beings can once again perceive and comprehend.

An important point here is not merely the inherent manipulability of digital information in itself but the fact that digital information has this manipulability at all stages: from the moment it is created or captured in digital form to the moment it is delivered to its user and beyond. In particular, consider the significance of media being manipulable at the point of delivery because it suggests nothing less than an unprecedented new paradigm for publishing and media distribution. The fact that media are manipulable at their point of delivery means something quite extraordinary: users of the media can shape their own experience of it. This means that manipulable information can be interactive information. We will examine the notion of interactivity in more detail later (pp. 13-17) but for now it is enough to understand it as a means of providing a dynamic experience, one which is controllable and influenced by its user's own preferences. Potentially, for example, a new generation of interactive products will offer users a way of finding their own path through material or of tackling it at a pace that suits them or of retrieving what they want quickly by making cross-referenced searches or important correlations. This is a dramatic contrast to the traditional passive, linear experience of media that characterises the analogue world. And it suggests a powerful new model for publishing and media distribution. To understand why, consider our past experience of media products.

Until the arrival of digital media, publishers and distributors of information, education and entertainment have enjoyed a single great privilege. They have been able to dictate what customers will view or read with only a modicum of selectivity left to the customer's discretion. Television scheduling has created the notion of 'channels' and ensured (give or take the intervention of video recorders) that certain programmes will be viewed and at certain preordained times. The same is true of radio. More fundamentally, both the television and film industry are founded-very successfully-on linear storytelling models.