A common language for hardware, software, and applications

Algorithms commonly used in automatic data processing are, when considered in terms of the sequence of individual physical operations actually executed, incredibly complex. Such algorithms are normally made amenable to human comprehension and analysis by expressing them in a more compact and abstract form which suppresses systematic detail. This suppression of detail commonly occurs in several fairly well defined stages, providing a hierarchy of distinct descriptions of the algorithm at different levels of detail. For example, an algorithm expressed in the FORTRAN language may be transformed by a compiler to a machine code description at a greater level of detail which is in turn transformed by the "hardware" of the computer into the detailed algorithm actually executed.