Special Types of Communication

An alphabet can be defined as a set of symbols representing the single sounds of spoken language, by which it is written.

There are other types of writing systems besides alphabets, and there are other types of communication besides writing.

For example, there is a broad range of sign languages, such as those of the Plains Indians and of the hearing impaired.

Codes such as the Morse code and semaphore are yet another type of communication. Though they are not written, their signals represent the letters of an alphabet.

Numbers, musical notation, braille and even sign-language might all be considered special types of writing. The great innovation in numbers, the use of zero as a place holder, was first used in India in the fifth century A.D., and was carried to Europe by the Arabs. It may have been inspired by Chinese or Babylonian numbers, written in grids, where an empty space represented zero.