Digital technology includes all types of electronic equipment and applications that use information in the form of numeric code. This information is usually in binary code–that is, code that can be represented by strings of only two numeric characters. These characters are usually 0 and 1. Devices that process and use digital information include personal computers, calculators, automobiles, traffic light controllers, video game consoles, cellular telephones, communications satellites, and television sets.
Most of the information people sense is analog in nature–that is, it varies constantly, and an infinite number of values can be assigned to the information. For example, the brightness of a light bulb dimmed gradually from on to off could be considered analog information. This infinite number of brightnesses can be quantized (broken up into ranges). If the possible brightnesses are broken into two ranges, then the values 0 and 1 can hold digital information relating to the brightness of the bulb. However, each of the two digits still represents a countless number of analog values. The ranges of brightnesses can be divided again and again, until there are thousands of ranges of values, each of which can be represented by a numerical value.
Once analog information has been quantized into digital information, it is impossible to perfectly reverse the process and re-create all of the possible analog signals from the corresponding digital signals. This is why most analog signals are represented by a great number of digital information levels. For example, the sound stored as digital information on a compact disc (CD) is broken down into 65,536 levels. A music player translates the digital information into analog information so that a speaker can convert it into sound waves.
Some devices process digital information using a tiny computer called a microprocessor. It performs calculations on digital information and then makes decisions based on the results. In such devices, computer chips called memory chips store digital information while it is not being processed. Software, which consists of instructions in the form of digital information, is used to control the sequence of operations in many devices that use digital technology.
