Over the past more than four decades since its inception in the 1960s, Geographic Information Systems (GIS) has
become more advanced and technologically mature in its geoprocessing and analytical tools. This paper provides an
overview of the evolution of GIS, and puts forward my viewpoint that the development of GIS is intimately related to
that of the three disciplines which constitute the core of GIS: Geography Science, Information Science, and Computer
Science. Based on the analysis on the future development of Geography Science, Information Science, and Computer
Science, as well as their crossover, infiltration, and integration trend, the paper provides an outlook on the prospect of
GIS being developed into a system of Geographic Information Science and realizing a "Digital Earth" engineering.