As time and technology progressed, people developed devices to communicate faster over greater distances. Items such as lanterns, mirrors, and flags were used to send messages quickly over an extended visual range.
All "out of earshot" communications have one thing in common: they require some type of "code" to convert human language to a form of information that can be packaged and sent to the remote location. It might be a set of letters in an alphabet, a series of analog pulses over a telephone line, or a sequence of binary numbers in a computer. On the receiving end, this code needs to be converted back to language that people can understand.
Dots and Dashes, Bits and Bytes
Telegraphs and early radio communication used codes for transmissions. The most common, Morse code (named after its creator, Samuel F. B. Morse), is based on assigning a series of pulses to represent each letter of the alphabet. These pulses are sent over a wire in a series. The operator on the receiving end converts the code back into letters and words. Morse code remained in official use for messages at sea almost to the end of the twentieth century-it was officially retired in late 1999.
Morse used a code in which any single transmitted value had two possible states: either a dot or a dash. By combining the dots and dashes into groups, an operator was able to represent letters, and by stringing them together, words. That form of on-off notation can also be used to provide two numbers, 0 and 1. Zero represents no signal, or off; and one represents a signal, or on, state.
This type of number language is called binary notation because it uses only two digits, usually 0 and 1. It was first used by the ancient Chinese, who used the terms yin (empty) and yang (full) to build complex philosophical models of how the universe works.
Our computers are complex switch boxes that have two states and use a binary scheme as well. The value of a given switch's state-on or off-represents a value that can be used as a code. Modern computer technology uses terms other than yin and yang, but the same binary mathematics creates virtual worlds inside our modern machines.