Abstract Borders: A Very Short Introduction challenges the perception of borders as passive lines on a map, revealing them instead to be integral forces in the economic, social, political, and environmental processes that shape our lives. The issue of borders includes considerations such as transnational communities, security threats from terrorist groups, migration regulation, rights of indigenous peoples, the legal status of the sea and outer space, environmental sustainability, and the emergence of neo-liberal economics. How have borders developed over time? What is their relevance today? Will we ever have a borderless world? Borders are likely to remain a hot topic across the social sciences and global headlines for years to come.