This introduction presents an overview of key concepts discussed in the subsequent chapters of this book. The book reviews life stories of twelve local shopping streets in six global cities around the world, traveling from New York to Shanghai by way of Toronto, Amsterdam, Berlin, and Tokyo. Like New York and Shanghai, all global cities develop the same reiterative ecosystem, an endlessly repeated patchwork of retail stores and services. The authors find remarkable similarities in the way they work and the risks they face, and outstanding differences in the way they respond to two major challenges of their time, globalization and gentrification. In recent years, global migration has brought super-diversity to most of the local shopping streets. Enriched by successive waves and forms of globalization, threatened at one time by abandonment and at another by gentrification, local shopping streets reflect the ebb and flow of urban social life, capital investment, and changing demographics.