Analog vs Digital

One might have easily heard this hundreds of times - "We are now entering the realm of the digital age" or something along that line. What does that mean, and how much did "digital" influence our life?

To put it simply, a digital system presents data by using discrete or discontinuous values. In other words, there are only yes and no, 0 and 1. Or it may be 1, 2, 3, 4 and so on, but nothing is envisioned or accepted between the numbers, so there is no such thing as 1.4 in a discrete system. If the system is 1.1, 1.2, 1.3, 1.4 and so on, then 1.27 is not accepted within the system as well. You get the picture.

On the other hand, its counterpart, an analog system, uses continuous values for data presentation. Within this system, the data could be divided down infinitesimally. Not satisfied by the data value of 1.2, feeling that it is not accurate enough? Drill deeper and you may get 1.26. Deeper more and you may get 1.257. And so forth the value goes.

One of the simpler example to illustrate the difference between these 2 systems is the thermometer. An analog thermometer will be that transparent glass stick with silvery mercury within, requiring you to read and try your best to find the closest reading between 2 thin horizontal lines. You know the mercury level stops between 37 and 37.1, but if you capture an image and enhance it, then do some calculation, you may get a more accurate result, say 37.07. Do a more detailed enhancing and maybe you get 37.072. You could never stop drilling deeper for an answer, because you could keep dividing the data down between numbers. The data is continuous.

A digital thermometer will be any one of those sophisticated alien thingie which shows the reading through a LCD display or such. Stuff it into your mouth, your ear or wherever you thinks best, wait for a moment, and beep comes the confirmation of a stable reading. Read the display: 37.1. And that's it. A sure answer without the need to scrutinize between lines for more detailed reading, because there aren't any. You will not get 37.15. You get it down to the lowest decimal available and stops there, and so the data is discontinuous or discrete.

Seems like a digital system has enhanced our life by making things simpler. So a digital system is just those computer's 0's and 1's right? Actually, no. Human has been using digital systems far longer than the invention of computers. Here are some of the more obvious but less thought of examples:

• Alphabets: Well, you couldn't get anything between A and B, or X and Y right?
• Morse code: Samuel Morse's famous code makes use of binary system's properties by constructing an alphabet through different combinations of long and short dashes.
• Smoke signals: Smoke signal used by Red Indians is actually an analog-digital conversion. The smoke column is continuous, but by covering the smoke and uncovering it, a digital signal could be generated and the combination of such plumes of discontinuous smoke can be interpreted as a message.
• Beacons: From ancient ones to modern ones, beacons signaled through a binary system - ON and OFF. 
• Go/No Go gauge: These gauges could be of any type, the most commonly seen will be the pin gauges, with their familiar cylindrical bodies. A hole's size could be checked through these gauges on whether they are manufactured within tolerance. 

Sources: Wikipedia: Digital