There are about 31 megacities of population size 10 million and above in the universe in 2016 as per UN-Habitat which is likely to be 41 in 2030. These gigantic habitats are significant as it has all the potential to convert into smart and global cities if configured for its sustainability. This creative configuration of megacities to smart and global is the outcomes of the book through city case studies. The vast population, cultural and ecosystem diversity, diverse institutional endowments, supply chains connectivity, global linkages and size of income and expenditure in these megacities creates opportunities for configuring to a smart global city. This chapter tries to understand the title of the book and surveys the growth, development, and distribution across geographic regions. Theories of global cities are studied briefly and finally ends up with broad approaches to configure these megacities to smart and global. In conclusion, the smart global economic community design strategy is detailed out and implemented in Kochi-Kannur megacity study. This chapter serves as a background of several case studies of megacity across many continents in this book.