Modernization, among the most dreaded words in IT, is finding new fans. Why? Cloud technologies and practices give software delivery teams new options for digital transformation that are far less career threatening than those of earlier eras. Cloud-native technologies also help teams improve customer experience and implement modular architectures that better adapt to change, enabling them to adopt cloud platform services that help eliminate old code and accelerate their enterprise transformation. This report defines the three key goals of modernization, five major modernization approaches, and five constraints that cloud leaders need to navigate.