The ARCS Model is a method for improving the motivational appeal of instructional materials developed by John Keller in 1984. It contains four conceptual categories - Attention, Relevance, Confidence and Satisfaction - that characterize human motivation. It also includes strategies specific to each category to enhance motivational appeal. The model can be applied to students, teachers and workers to identify motivational characteristics. Though widely used, it is not a simple model and further research is needed as motivation can vary between individuals.