The first successful system of electrical communication was the telegraph, which was invented by Samuel F.B. Morse in the year 1832. The telegraph operators used a code of clicks to send the messages. If the key pressed for a short time it is the Morse code called ‘dot’ and if the key pressed for a long-time it is ‘Dash’. A sample Morse code is shown below:
If it is observed logically, various innumerable combinations of dots and dashes of any kind of words (even sentences) can be written utilizing the above code. In the same way, binary digits also be utilized to make such various innumerable combinations. These may be considered as Binary Codes.
Other than the commonly used 8421 code or BCD code, other Binary Codes like 2421 code, 5211 code, reflective code, sequential code, non-weighted code, excess-3 code and Gray code are also popular.