In the development of information systems in business, informal specifications through graphical modeling have been used at least since late 70s. We shall be studying many of these modeling tools. Recently, formal specification languages (such as Larch, VDM, Z, FOOPS and OBJ) have been developed. While their use in business systems development is in its very early stages, they are expected to play an important role in the future. These formal specification techniques attempt to mathematically specify structure, function, and behavior of information systems.