The aim of our Grid Computing learn at Sun is to take Cluster and Grid computing onto the next level of widest acceptance. For this purpose, we present a three-tier Grid architecture which relates to an intuitive model, including Cluster, Campus and Global Grids, which allows users to embrace Grid Computing starting with their current compute clusters, and moving to the next level of Grid implementation in an evolutionary way. In addition, we present a complete Grid software stack for all three Grid stages, which contains modules developed at Sun and by our partners.