The idea of a circular economy is attracting increasing attention from researchers, funding agencies, policy makers and industry. Broadly speaking, the circular economy promotes a future in which linear 'make-use-dispose' cultures are replaced by more circular models. In EU visions of a circular economy, ideas about waste management, recycling, reuse, resource efficiency, sharing economies, maintenance and repair cultures are all woven together in multiple ways. However, according to the basic laws of thermodynamics full circularity is not possible: the economy cannot be circular! What, then, does 'circularity' mean and what is so special about the Circular Economy? The first chapter brings together articles from the inaugural issue of The Nexus Times (TNT) that aimed to address these questions and shed light on some of the challenges circular economy initiatives are facing. .