Although programming languages are many in number and diverse in nature, nearly all of them rely on an essential set of a small number of basic concepts. Knowledge of these concepts is essential to programmers, compiler writers, and others.

A programming language, like any formal language, must have a specific alphabet associated with it. As almost all programming languages have been designed in the U.S. and other English-speaking countries, the 7-bit ASCII character set that encompasses the Roman characters used in English is the most common alphabet, used with older programming languages such as C. However, this does not allow for the use of umlauts and other singular features--these are found with characters in European languages (such as Ç, ä, etc.) Nor does the 7-bit ASCII allow characters from other scripts such as Chinese to be used. Hence, newer languages often allow a...