Book excerpt: This book addresses several aspects of environmental sustainability awareness and priorization, explores ways to use resources and processes more responsibly, and describes the strategies, models and tools required to overcome various challenges. Sustainable and green IT are used to minimize the current ICT recycling problems which are harming our planet. The book discusses the new green information technologies as alternatives to conventional ICT, which have significantly harmed nature, and examines how to make recent technologies such as cloud computing; social networking; smart technology; blockchains, IoT (internet-of-things); and big data sustainable. Exploring sustainability awareness and importance among individuals and organizations in the developed and developing countries, most of the contributions conclude that sustainability should be considered a duty in order to change mindsets, attitudes and actions so as to preserve our planet. Furthermore, it examines the green information technology strategies and models.