Models are built on the assumption that any given process and relation can be expressed in a formal mathematicalstatement(s) or equations, and they all can be inter-connected to run iteratively. Development of crop models started first in1940s, but very few in the scientific community believed that the complex bio-physical and morphological processes of plantgrowth could be described mathematically, except possibly under controlled environments. In the early 1980s for the first timemodels were used as Decision Support System (DSS) tool. Soon after enhanced understanding of agro-ecosystem processesand synthesization of this to predict outcomes helped apply models to control and manage outcomes. The first product thatcame out of this effort was Decision Support System for Agro-Technology Transfer (DSSAT) model followed by AgriculturalProduction Simulator (APSIM) model. Soon Consultative Groups for International Agriculture Research (CGIAR) centresstarted to develop and work with models. Development in modeling science and natural progression of scientific research wenthand-in-hand. Since then models have been used in crop management, yield gap analysis, abiotic stress impact studies,potential yield, plant disease forecasting, inter-cropping and livestock-crop interaction studies. Soon models were used topredict climate change impact on food security and socio-economic issues at regional and global scale. Since 2010 modelingwork expanded to multi-model inter-comparison, climate change and climatic variability impact assessment, quantifyinguncertainties in models for further development, genomics studies, crop improvement programs, regional and global foodsecurity issues, GxExM and GxExMxS interactions, conservation agriculture (CA), agro-forestry and tree-crop-livestockinteractions and tuber crops, and also as DSS tool for crop management under current and future climates.